fix NPE in installer fragment

 if the first thing you do after installing the ROM
 is go to InstallerFragment and try to check
 one of the checkboxes, you get a NPE because
 prefs haven't been loaded yet.

Change-Id: I515fffc709822a4fea7d7cd82f50ac59a5c79af3
Signed-off-by: Arnav Gupta <championswimmer@aokp.co>
Merge "fix NPE in installer fragment" into kitkat