Fix card display issues on lower density screens.

Removed the text line restriction for simple_message_card, as it isn't
necessary. Changed the layout of dashclock cards to display more lines
before ellipsizing and have a dynamic height. Fix minor color display
issue in Trebuchet.

Change-Id: I901c0a23b44325d8c133dc71b5c07e4c8137876c
Fix Undo Bar appearance during Google Now use.

Sometimes the Undo Bar can be in a visible state when a Trebuchet user
toggles to use Google Now instead. Since CM Home is used to provide a
transition effect, the Undo Bar should not be visible at that time. Fix
this by setting visibility to GONE when setShowContent(false) is called.

Change-Id: I4f48096500c0dde6dacead3b59ff4c4eb050c30f