Fixed math problem randomness. Fixed font issues for different categories.
Fixed text to speech exception

Small exception caused by not stopping and shutting down the text to
speech instance.
Added user account table to database. Added fragment inside learn content to flip through images and words.
Removed library projects that we aren't using
Merge branch 'dev'

Conflicts:
	DataDroid/project.properties
	ImageViewEx-develop/project.properties
	ImageViewEx-develop/test/project.properties