jcabi-github requires Hamcrest to get a http request

I tried to use `jcabi-github` library in order to get some statistics from repos and during the first run get the next exception:
```java
Exception in thread "main" java.lang.NoClassDefFoundError: org/hamcrest/Matcher
at java.base/java.lang.Class.getDeclaredConstructors0(Native Method)
at java.base/java.lang.Class.privateGetDeclaredConstructors(Class.java:3429)
at java.base/java.lang.Class.getConstructor0(Class.java:3634)
at java.base/java.lang.Class.getDeclaredConstructor(Class.java:2810)
at com.jcabi.http.request.DefaultResponse.as(DefaultResponse.java:161)
at com.jcabi.github.RtJson.fetch(RtJson.java:76)
at com.jcabi.github.RtRepo.json(RtRepo.java:250)
at com.jcabi.github.RepositoryStatistics.toMap(RepositoryStatistics.java:70)
at com.jcabi.github.RepositoryStatistics$Smart.integer(RepositoryStatistics.java:282)
at com.jcabi.github.RepositoryStatistics$Smart.forks(RepositoryStatistics.java:226)
at filter.statistics.GitHubMetrics.cells(GitHubMetrics.java:30)
at filter.statistics.StatisticsComposite.cells(StatisticsComposite.java:29)
at filter.statistics.StatisticsCaseLibrary.cells(StatisticsCaseLibrary.java:35)
at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
at java.base/java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:1006)
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
at filter.Report.make(Report.java:28)
at filter.FilterLibraries.main(FilterLibraries.java:198)
Caused by: java.lang.ClassNotFoundException: org.hamcrest.Matcher
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
... 22 more
```

The reason is obvious - my app can't find `Hamcrest` classes in the classpath. It is rather confusing. Why do I need to keep a testing library in runtime? Of course, adding the next library helped me (pay attention to the `scope`):
```xml

org.hamcrest
hamcrest
2.2
compile

```
But maybe it is better to fix the plugin to avoid usage of testing libraries in runtime?