Correctly loading TTF. Need to specify directory and filename suffix.

In the future CocosSharp should handle this more gracefully. In particular,

* debug warn users when TTF file was not found and default font will be used
* allow users to specify filename without suffix to be consistent with label types
* respect the ContentSearchPath specified by app delegate to allow users to specify absolute filename
Added title image for Android

* Using a native .png on Android will result in a white border around the image
* This asset was built with the MonoGame Content Builder command line tool on Mac
Merge pull request #6 from rtabbara/master

TTF and Android image changes