Rework thumbnail handling

Since ids of media file are usually not continuous, the original file of thumbnail are
sparse. When there are big numbers files on ex\
ternal storage, the size of this file will be horrible.
Ex, when the id is 20000, then the .thumbnails/.thumbdata3-xx file will be 50000*10k = 488.28M.
Can refer http://stackoverflow.com/questions/12396715/android-huge-thumbdata4-file-in-dcim-folder
Because after 4.0, MediaProvider will scan any files, this will be a big problem. So I modify MiniThumbFile.java to avoid this.
According to the id, we now produce an index file. In this index file, one id will use BYTES_PER_MINTHUMB_INDEX(8) bytes in offset (i\
d+1)*BYTES_PER_MINTHUMB_INDEX. The data of these 8 bytes is the index of thumbnail file. The first BYTES_PER_MINTHUMB_INDEX bytes kee\
p next available index. And when you need insert a thumbnail, the index increase by 1. In this way, the block data in thumbnail file \
will be continuous. And thus unnecessary zero paddings will not be saved.

Change-Id: I66005dd69b0a5c8f4353bd7a8225d163a654fd2d
Align the status bar date to the bottom

As in AOSP. Also occupy the whole height area so that the date can be
easily clicked.

Change-Id: I66e5b7a754f27571f987657cc7ccd2ef3bef3f9e
Add method to PowerManager that allows querying the lowest possible
brightness.

Used by the auto-brightness adjustment to adjust the sliders.

Change-Id: Idb58fd86dee1a053fe858291be6c9b3169ac4247
SystemUI: always use transparent notification shade

Devices with less than 512MB of memory have a solid
black notification shade. Remove the isHighEndGfx()
check to force a transparent notification shade on
all devices.

Change-Id: I9a68a2a8b0d36685f8899f3bbed43bb6bccb47b1

Conflicts:
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java
Smooth Spinners: Makes the loading "spinner" animation smoother in non-holo apps

The loading "spinner" animation is quite jerky by default when the progress xml's from
drawable are called in applications that don't use the holo progress animation. The holo
"spinner" animation is already smooth by default. This makes every other "spinner"
animation smooth.

We've been changing this value in all ROM's we release, both AOSP and CM based ones
as well as stock ROM's, since it gives a more polished look to the entire system. In the past
3 years we've been using this small tweak we have not noticed anything that would
adversely affect battery life or system operations as a whole.

Rebased to cm-10.1 by Kristof Petho

Change-Id: I617d197c2ff4f1a27e96dbc206c24c27036e18d6