Fixing alpha of workspace components being changed at too many places

> Hotseat alpha is changed by all-apps controller, workspaceStateTransition
and overlay transition. Created a 3 state alpha for hotseat and pageIndicator
> Simplified the page-background and alpha animation during state transition
by moving the code in the same if block
> Disabling partial page fading when pull-up all apps is enabled. This fixes
the bug when pressing home with all-apps opened causes other pages to disappear.

Change-Id: I4a75b89af12b48e9fbc49514e641fd424d07199c