replace groupId `android.android` with `android`

replace groupId `android.android` with `android`; make this section more visible
Merge pull request #228 from PaulVI/patch-1

replace groupId `android.android` with `android` in README
reverted back to thirdparty repo as default
upgraded to latest parent release
Use the correct source.properties directory for the google-gdk-19 module

This commit overrides the parent pom's properties-maven-plugin
configuration in order to specify the gdk.directory as the correct path
to the source.properties file.

fixes #248
Merge pull request #249 from royclarkson/GDK-DIR

Use the correct source.properties directory for the google-gdk-19 module