Support project flavors for the android-library plugin

When this code was originally written, flavors were not supported by the android-library plugin. As such, when building a variation name, an optimization was put in place to skip the flavor as a piece of the ultimate variation name in the case of the android-library plugin. Now that flavors are supported for libraries, this optimization actually breaks the roboelectric plugin with an error such as "Error:Cannot add a SourceSet with name 'testDebug' as a SourceSet with that name already exists.". This is because a library today that *does* have flavors will cause this plugin to attempt to add the same-named test sourceset for each flavor+buildtype.
Testing test-task creation for android app and library flavors.
Add jvmArgs documentation to README.
Merge pull request #71 from kageiit/add_jvmargs_readme

Add jvmArgs documentation to README.
Merge pull request #70 from samdozor/support-library-flavors

Support project flavors for the android-library plugin.
Bump version number to 0.13.1.
Fix for APK splits
Merge pull request #77 from frownlee/apk-splits

Fix for APK splits.
Set source and target compatibility to 1.6.
Bump version number to 0.13.2.
Add extension properties for test parallelization.
Use HTTPS for Gradle Wrapper for better security.
Updated Android Gradle plugin to 0.13.2
Updated Travis configuration
Merge pull request #85 from ChristianBecker/travis

Updated Travis configuration.
Merge pull request #83 from ChristianBecker/gradle_https

Use HTTPS for Gradle Wrapper for better security.
Merge pull request #84 from ChristianBecker/android_gradle_0_13_2

Updated Android Gradle plugin to 0.13.2.
Merge pull request #82 from mattott/master

Add extension properties for test parallelization.
Use CompileClasspath of the TestVariant to support AAR test dependencies.
Added test for proper classpath creation.