Bug fixes the encryption code

Fixes MOBILE-1301, MOBILE-1380, MOBILE-1381, MOBILE-1383 along with
other improvements and fixes to the encryption code.
Review comment changes
Merge pull request #73 from ldjagger/master

MOBILE-1301, MOBILE-1380, MOBILE-1381, MOBILE-1383
Merge remote-tracking branch 'parent/master'

Conflicts:
	alfresco-mobile-android/res/values/strings.xml
	alfresco-mobile-android/src/org/alfresco/mobile/android/application/MainActivity.java