ArmsMVP不支持Android5.0以下的设备

Android4.3系统
```java
java.lang.RuntimeException: Unable to start activity ComponentInfo{me.jessyan.mvparms.demo/me.jessyan.mvparms.demo.mvp.ui.activity.UserActivity}: java.lang.RuntimeException: Failed to call observer method
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2214)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2264)
at android.app.ActivityThread.access$600(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1259)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5136)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.RuntimeException: Failed to call observer method
at androidx.lifecycle.ClassesInfoCache$MethodReference.invokeCallback(ClassesInfoCache.java:226)
at androidx.lifecycle.ClassesInfoCache$CallbackInfo.invokeMethodsForEvent(ClassesInfoCache.java:194)
at androidx.lifecycle.ClassesInfoCache$CallbackInfo.invokeCallbacks(ClassesInfoCache.java:185)
at androidx.lifecycle.ReflectiveGenericLifecycleObserver.onStateChanged(ReflectiveGenericLifecycleObserver.java:36)
at androidx.lifecycle.LifecycleRegistry$ObserverWithState.dispatchEvent(LifecycleRegistry.java:361)
at androidx.lifecycle.LifecycleRegistry.forwardPass(LifecycleRegistry.java:300)
at androidx.lifecycle.LifecycleRegistry.sync(LifecycleRegistry.java:339)
at androidx.lifecycle.LifecycleRegistry.moveToState(LifecycleRegistry.java:145)
at androidx.lifecycle.LifecycleRegistry.handleLifecycleEvent(LifecycleRegistry.java:131)
at androidx.lifecycle.ReportFragment.dispatch(ReportFragment.java:123)
at androidx.lifecycle.ReportFragment.onActivityCreated(ReportFragment.java:76)
at android.app.Fragment.performActivityCreated(Fragment.java:1703)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:903)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1057)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1039)
at android.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:1840)
at android.app.Activity.performCreate(Activity.java:5136)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2178)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2264) 
at android.app.ActivityThread.access$600(ActivityThread.java:144) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1259) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:137) 
at android.app.ActivityThread.main(ActivityThread.java:5136) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:525) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
at dalvik.system.NativeStart.main(Native Method) 
Caused by: java.lang.VerifyError: okhttp3/internal/platform/Android10Platform
at okhttp3.internal.platform.Platform.findPlatform(Platform.java:201)
at okhttp3.internal.platform.Platform.(Platform.java:78)
at okhttp3.OkHttpClient.newSslSocketFactory(OkHttpClient.java:292)
at okhttp3.OkHttpClient.(OkHttpClient.java:258)
at okhttp3.OkHttpClient$Builder.build(OkHttpClient.java:1040)
at com.jess.arms.di.module.ClientModule.provideClient(ClientModule.java:132)
at com.jess.arms.di.module.ClientModule_ProvideClientFactory.provideClient(ClientModule_ProvideClientFactory.java:68)
at com.jess.arms.di.module.ClientModule_ProvideClientFactory.get(ClientModule_ProvideClientFactory.java:53)
at com.jess.arms.di.module.ClientModule_ProvideClientFactory.get(ClientModule_ProvideClientFactory.java:14)
at dagger.internal.DoubleCheck.get(DoubleCheck.java:47)
at com.jess.arms.di.module.ClientModule_ProvideRetrofitFactory.get(ClientModule_ProvideRetrofitFactory.java:48)
at com.jess.arms.di.module.ClientModule_ProvideRetrofitFactory.get(ClientModule_ProvideRetrofitFactory.java:13)
at dagger.internal.DoubleCheck.get(DoubleCheck.java:47)
at com.jess.arms.integration.RepositoryManager.obtainRetrofitService(RepositoryManager.java:96)
at me.jessyan.mvparms.demo.mvp.model.UserModel.getUsers(UserModel.java:63)
at me.jessyan.mvparms.demo.mvp.presenter.UserPresenter.request

```

Start with the failure at ClientModule.java:132 and the stack trace through okhttp3.internal.platform.Platform.findPlatform, which reports Android10Platform on Android 4.3. Reproduce the startup failure on a device or emulator below Android 5.0, then verify that the application starts and the user request succeeds on that platform.

索引モデルが issue の本文から書いたものです。