game_engine. Prepration to add AdMob to game activity.

Change game activity layout to linear layout.
Add game linear layout.
Game view added to linear layout.
Add reference to google play services in test game.
game_engine. Create game activity layout in code.

There is a bug in android that causes find view by id to return null, when the layout resource is declared in the game library.
To avoid this issue the game activity layout is now created when intiailizing the game activity.
Add an initialize view utility method.
Add an initialize game view utility method.
Both replace the old initialize view method.
game_engine. Add creation of admob banner.

Add admob data to game bundle - ad mob id, and test devices.
Create the admob banner in game activity.
Admob data is stored in a resource admob.xml.
Add admob.xml to gitignore - must never be part of the project.
Load admob data from admob xml in test game main activity.