Move process stats screen into memory screen.

 - Move process stats from developer options to top level
   settings item.
 - Some minor UI changes to the top of the page
 - Major UI updates to detail page, now shows info with processes
   as pref categories and services as prefs, with a way to kill
   them (taken from Running Services page).
 - Some major refactorings in code, in attempt to make it more
   usable
 - Added color bar on per app basis to visualize the avg/max
   relationship
 - Updated the way avg is calculated across multiple entries in
   ProcStatsPackageEntry to be more accurate
 - Change the way max memory is calculated in
   ProcStatsPackageEntry to be less accurate but more useful

Bug: 19443802
Change-Id: Ia6aaabe42c415c50997a09bfb814a6f6e5731772