Added logout function
Added notification methods
Added new preferences
Fixed bugs (clear cache and timestamp)
Merge branch 'master' into alcros-dev

Conflicts:
	Vertretungsplan/src/com/inf1315/vertretungsplan/AllAsyncTask.java
Included InfoActivity in Settings
Merge remote-tracking branch 'origin/master'

Conflicts:
	Vertretungsplan/res/layout/preferences.xml
	Vertretungsplan/res/values/strings.xml
	Vertretungsplan/src/com/inf1315/vertretungsplan/LoginActivity.java
	Vertretungsplan/src/com/inf1315/vertretungsplan/PlanActivity.java
	Vertretungsplan/src/com/inf1315/vertretungsplan/SettingsFragment.java
Adapted settings texts to android guideline