Fix Settings Panel bug causing frozen overview.

Previously, toggling search panel would freeze Overview mode
until the user exited back to the regular launcher. Also, the current
page would be lost. Fix this by computing the new scroll bounds
immediately when the setting is toggled.

Change-Id: Ib3587cfcea61e15b3d8b280113ce986cc57f2f9d
Fix CMHome related bugs.

1. If "Search Panel" is enabled, when dragging an app icon to a new
   screen, the 'glow' effect for the next page will highlight the entire
   height of the screen instead of just the workspace view height as
   expected. This bug exists in launcher3 and GEL. Fixed here.
2. Older versions of the Google Search app do not respond to
   Intent.ACTION_ASSIST and can crash Trebuchet when it tries to launch
   Google Now that way. Instead, use searchManager.globalSearchActivity(),
   which matches the method we use to detect Google Now's presence anyway
   (+ being "search app" agnostic!)

Change-Id: I5e5b3504272e2a2ca656accc32164d1ae9e52077
Merge remote-tracking branch 'cm/cm-11.0' into cm-11.0