Battery percentage on status bar - done right!

This is by far the most requested feature! First try of implementing this
didnt go very well. Hope this solves the issue and gets merged ASAP.

- Added optional Percentage-Status-Bar-Battery
- Displaying text next to a mini battery icon
- no additional resources added!
- no color pickers were harmed in the process!
- mini battery icon build from a scaled slice, cutted from the 4th vertical
  line of pixels from the original battery icon of the matching charge level
- this way, themes will be obeyed, as long as those themes dont change the
  basic layout of the battery icon too much. in such cases (i.e. theme features
  some kind of circle mod) this option should be disabled anyways
- Added also an option to disable clock in status bar, so our Status-Bar-Tweaks
  submenu got more than one entry - i look forward for it to grow in cm7.1
- Changed as few original files as possible. mainly since status bar is most
  likely a place of changes by google. CmBatteryText and CmBatteryMiniIcon do
  most of the work. Original files needed a SettingsObserver of course.

The usual screenshots: http://kan.gd/sc

Needs review on MDPI and LDPI devices

Change-Id: I187710784909eca9d7271f021aa16ab94212f3e6