Adding instrumentation runner options to be passed down via Map/Bundle

Initial process of adding instrumentation runner options as define on the Instrumentation test runner documentation.

The options are passed as HashMap via instrumentationOptions:

```groovy
android {
    defaultConfig {
        testInstrumentationRunner "android.test.InstrumentationTestRunner"
        instrumentationOptions coverage: 'true', coverageFile: "/sdcard/myFile.ec"
    }
}
```

The options are generic and will be passed as bundle to the instrumentation runner. This can also be done in code:
https://github.com/novoda/gradle-android-jacoco-plugin/blob/master/plugin/src/main/groovy/com/novoda/gradle/android/jacoco/plugin/JaCoCoPlugin.groovy#L55

This PR does not include code coverage per say as it is fullfilled in another plugin here:
https://github.com/novoda/gradle-android-jacoco-plugin