Don't try to set service.bootanim.exit

init has never allowed the bootanimation code to
set service.bootanim.exit, and has always generated the
dmesg error message

  <3>[   17.644615] init: sys_prop: permission denied uid:1003  name:service.bootanim.exit

Since setting this property has no effect and never worked, delete
the code which tries to do it.

Change-Id: Idacc5467d85479a8cf974702af8895011be585ea
Fix: Lockscreen Blur Rotation

Credits to David L.-W (David96)
https://github.com/AOSPAL/android_frameworks_base/commit/f80b748

Modifications made to address the issues noted in original commit

Change-Id: I721e7f8554433b903209da5587ac1dfcd83420cd

Conflicts:
	packages/Keyguard/src/com/android/keyguard/KeyguardViewManager.java
Fix preference puts with "null" values.

Null values were being written out as <null /> elements in the
XML prefs file (as expected). This allowed the getFoo() functions
to work correctly because they treated null values as missing mappings
but containsKey would fail.

bug: https://code.google.com/p/android/issues/detail?id=64563
Change-Id: I1f466d01db96bf26e208d4fed3a6f257228bea5d