Support Android SDK Deployer platform dependencies

The Maven Android SDK Deployer by default uses 'android' as the group id
instead of 'com.google.android'.  I believe Google with Gradle is starting to
move toward the com.google.android group ID but for legacy projects the
'android' groupID still needs to be supported.

The Android app test suite now runs against the latest Android API
version. This requires that the Maven Android SDK Deployer should be
executed before the test suite runs.

Documentation and Travis Ci scripts have been updated accordingly.

This issue fixes:

https://github.com/rgladwell/m2e-android/issues/181
Fixed regressions caused new platform dependencies.

The Maven platform dependencies published by the Android SDK Deployer
(https://github.com/mosabua/maven-android-sdk-deployer) lack transitive
dependencies. This causes a number of tests verifying these depencies
are added to JUnit launcher classpath to fail.

This can be fixed by adding platform provided dependencies to the
provided scope of your Android project and the tests have been modified
to reflect this.

Some tests verifying the absence of Android platform dependencies have
been weakened to allow the tests to pass. This means that classes may
appear twice in the Eclipse workspace classpath if they're provided by
the Android platform.