Make activity tracking reliable (robotium issue 179)

Use the recommended constructor for robotium.Solo()

This makes activity tracking work reliably when the main activity of the
application starts other activities immediately.

See https://code.google.com/p/robotium/issues/detail?id=179

Also fix some warnings at the same time.

Also tweak some build settings
* aapt is no longer a batch file on windows
* assets shouldn't be a source director for Eclipse
* libraries don't need to be added to the build path manually in Eclipse