implemented autosync in background
implemented synchronization after learning
changed some texts
implemented network problem handling
now catching databse locked exception on synchronization
updated image
imprved update schedule, added back button to learning activity
Merge branch 'devel' into releasecandidate2

Conflicts:
	src/com/srsoftware/allergyscan/AllergenSelectionActivity.java
	src/com/srsoftware/allergyscan/LearningActivity.java
	src/com/srsoftware/allergyscan/MainActivity.java
	src/com/srsoftware/allergyscan/SynchronizeActivity.java