SDK / exoplayer

Enable gradle test code coverage for the library modules that aren't affected by 'stuck in endless loop' issue

'library-core' is still affected by https://code.google.com/p/android/issues/detail?id=226070

Code coverage report can be generated for the rest of the modules by:
./gradlew :[module name]:createDebugCoverageReport
Report is generated under:
[module folder]/buildout/reports/coverage/debug

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