framework: Custom lock screen background [1/2]

Patch Set 1:    * port the custom lock screen feature from
                  ics (http://review.cyanogenmod.org/#/c/16915)

                * thanks to Danny Baumann, who reworked the
                  framework part to work after Jelly Bean 4.2
                  lockscreen changes

Patch Set 2-3:  * remove obsolete files

Patch Set 4-7:  * revert XML changes

Patch Set 8,9:  * rebased

Patch Set 10:   * fix minor code style

Change-Id: I800506a9f9e001f659ee29b8b2dbe3464e5198f9

Conflicts:
	policy/src/com/android/internal/policy/impl/keyguard/KeyguardHostView.java
Lockscreen : Add custom background overlay

Adds an overlay on top of custom images/colors to better match
stock appearance.

https://jira.cyanogenmod.org/browse/CYAN-1280

Change-Id: I1210d208de912e7f6a1941284f1fe1ff0776ab48

Conflicts:
	policy/src/com/android/internal/policy/impl/keyguard/KeyguardViewBase.java
Lockscreen : Use correct filter for background

Switch over to SRC_ATOP filter instead of using MULTIPLY.

Change-Id: I6b8dac563136cd10b48b6fc6c0ecb2265d0e0b04