Switch to JPEGs for AOSPA Wallpapers

Some parts of Android expect images to be in JPEG format - Therefore this commit removes the PNGs & puts in the JPEG versions of the wallpaper.

Change-Id: Ic0b4731b5c6dab5212e881c821280372148011e7
Themes: Force recompiling common resources when scanning theme

If a theme is re-installed multiple times and in less time than
the 3 minute timout for common resources, it is possible for the
installation to fail because it does not compile the common resources.
This is not something an average user would encounter normally but
theme designers that are working on there theme and constantly
installing updates have a better chance of encountering this situation.
We simply remove the theme from mAvailableCommonResources which will
allow them to be recompiled.

Change-Id: I04b64645157dbb1d0c26fab95c851b34bfff3f42
On-The-Spot: Underp Safe-Headset one once for all and code cleanup:

After Gif support, context managing went derped resulting in the old NPE.
Valter's fix restored all the contexts that are used within system one that
we need just to read&write to system, but dialog's builder needs one created
by the ThemeEngine.

* Fix dialogs not being themed:
  Pass themed context only to dialog builder by crating one when needed.

* Cleanup implementation:
  Restore all normal system contexts and add an helper method to generate
  a theme context to be used by AlerDialog.Builder() for pulling themed resources.

PS3: Miscs
PS4: Code cleanup
PS5: Commit message cleanup

Signed-off-by: Carlo Savignano <stevewatersy@gmail.com>
Change-Id: I1e3f9dce7dd448306db0364ab6e1ff8a71160729
Merge pull request #23 from AOSPA/kitkat

:O