fix some lint warnings

- remove unused xml files in res/color
- fix messup in device_list.xml; sp was used instead of dp;
  textview not needed (no text), because just a divider for
  list parts.
- remove useless parent LinearLayout
- remove useless sub layouts (no id, no background, no children,
  no style)
- use Double.valueOf instead of new Double()
- modify Manifest of test and uitest package:
    disable warnings for ApplicationIcon and Backup
remove unused code

- IconMenuAdapter and CustomIconContextMenu not needed (any more)
- remove res/color directory
- remove unused colors
fix lint warnings

- ignore SmallSp warning in AboutDialog; the text has to be that small
- supress NewApi warnings for ABS style items
- replace hardcoded /sdcard directory in Filetests
- fix warning #recycle(); MotionEvents should always call recycle()
Merge pull request #562 from Catrobat/fixLintWarnings

Fix some lint warnings