CLOSED - task 372: Move all preference string to be static attributes of
PrefsActivity
https://github.com/DigitalCampus/oppia-mobile-android/issues/issue/372
CLOSED - task 379: Add settings option to disable logout
https://github.com/DigitalCampus/oppia-mobile-android/issues/issue/379
comment for now...
CLOSED - task 380: Add settings option to disable deleting of courses
https://github.com/DigitalCampus/oppia-mobile-android/issues/issue/380
Merge remote-tracking branch 'upstream'

Conflicts:
	src/org/digitalcampus/oppia/fragments/OppiaWebViewFragment.java
	src/org/digitalcampus/oppia/task/DownloadCourseTask.java
	src/org/digitalcampus/oppia/task/DownloadMediaTask.java
	src/org/digitalcampus/oppia/task/LoginTask.java
	src/org/digitalcampus/oppia/task/RegisterTask.java
	src/org/digitalcampus/oppia/task/ResetTask.java
	src/org/digitalcampus/oppia/task/SubmitQuizTask.java