Proguard configuration

Hi David,

Could you help with the proguard configuration:

```
Warning:com.github.davidmoten.rx.Jaxws$ObservableAdapter: can't find superclass or interface javax.xml.bind.annotation.adapters.XmlAdapter
Warning:com.github.davidmoten.rx.Jaxws$ObservableAdapter: can't find referenced class javax.xml.bind.annotation.adapters.XmlAdapter
Warning:com.github.davidmoten.rx.Serialized: can't find referenced class com.esotericsoftware.kryo.Kryo
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder: can't find referenced class com.esotericsoftware.kryo.Kryo
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder: can't find referenced class com.esotericsoftware.kryo.io.Output
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder: can't find referenced class com.esotericsoftware.kryo.io.Input
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder: can't find referenced class com.esotericsoftware.kryo.Kryo
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder$1: can't find referenced class com.esotericsoftware.kryo.io.Output
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder$2: can't find referenced class com.esotericsoftware.kryo.io.Output
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder$2$1: can't find referenced class com.esotericsoftware.kryo.Kryo
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder$2$1: can't find referenced class com.esotericsoftware.kryo.io.Output
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder$3: can't find referenced class com.esotericsoftware.kryo.io.Output
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder$4: can't find referenced class com.esotericsoftware.kryo.io.Input
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder$5: can't find referenced class com.esotericsoftware.kryo.io.Input
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder$6: can't find referenced class com.esotericsoftware.kryo.io.Input
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder$7: can't find referenced class com.esotericsoftware.kryo.io.Input
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder$7: can't find referenced class com.esotericsoftware.kryo.Kryo
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder$7: can't find referenced class com.esotericsoftware.kryo.io.Input
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder$7: can't find referenced class com.esotericsoftware.kryo.Kryo
Warning:com.github.davidmoten.rx.Serialized$KryoBuilder$7: can't find referenced class com.esotericsoftware.kryo.io.Input
Warning:com.github.davidmoten.rx.testing.TestSubscriber2: can't find referenced class org.junit.Assert
Warning:com.github.davidmoten.rx.testing.TestingHelper$TestSuiteFromCases: can't find referenced class org.junit.runners.Suite$SuiteClasses
Warning:com.github.davidmoten.rx.testing.TestingHelper$TestSuiteFromCases: can't find referenced class org.junit.runners.Suite
Warning:com.github.davidmoten.rx.testing.TestingHelper$TestSuiteFromCases: can't find referenced class org.junit.runner.RunWith
Warning:com.github.davidmoten.rx.testing.TestingHelper$TestSuiteFromCases: can't find referenced class org.junit.runners.Suite
Warning:com.github.davidmoten.rx.testing.TestingHelper$TestSuiteFromCases: can't find referenced class org.junit.runners.Suite$SuiteClasses
Warning:there were 75 unresolved references to classes or interfaces.
```
Thanks in advance.