It was coded pretty badly, so I cleaned it up. Most notably, it used
a static instance of the Activity, which is a huge no-no which
creates memory leaks. The irony is, it already had a reference to the
Activity used correctly in the constructor. One memory-leak fixed,
29 more to go (LibreOfficeMainActivity holds that static Activity
object which needs fixing). Also, simplified the "bottom toolbar"
in preparation for the CoordinatorLayout implementation which will
allow the activity to have fancy animations and smart interactions.

Change-Id: I31aa117f6179910db73a5256b0a287357e1dec83
Reviewed-on: https://gerrit.libreoffice.org/33010Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: jan iversen <jani@documentfoundation.org>