Updating travis-ci config to use android SDK symbolic names instead of numeric id
Merge pull request #283 from imartinezortiz/travis-android-fix

Updating travis-ci config to use android SDK symbolic names
Updated targetSdkVersion to leatest (19).

Fixes #198
Updated engine-android to use latest targetSdkVersion.
Rebased and fixed editor-android sdk version.
Updated android-maven-plugin to latest: 3.9.0 release candidate 1
Changelog: https://code.google.com/p/maven-android-plugin/wiki/Changelog