Refinement pass on editing summary panel.

Updates to canned edit summary choices and wording to sync
with Kenan/Vibha's list.

Used designer's color scheme for canned edit summary buttons.

Centralized WMF colors in single file - changed various places
to reference these colors.

Fixed annoying issues causing search keyboard to be hidden
unexpectedly.

Change-Id: Icc17003b1d167c295c3229bb53d2aadea8f6302e