Minimum size for component views to prevent losing component controls

GH-207
Operating table now takes on the same background as the surface
Updated tablets to use a template in prep for changing them to a
pulldown
Refactored tablets to be generic / independent of Strut.
Styled the new tablets, made surface chooser visible under all modes
"moved" the css and class buttons.  This needs to be revisited.
Allow overflow of slideTable so elements off the grid are still selectable.

This will make it so the contents scroll rather than the editor itself.
Made pulldown toggleable
Created a white markdown icon
Moved responsibility for tablets into the header
Updated tablets to hook into the service registry for their content
Moved button to widgets
Wired all the services together for the new menu area
Merge pull request #216 from KZeni/patch-1

Allow overflow of slideTable so elements off the grid are still selectable
Expanded background chooser to include options for single slides and all
slides
Updated chooser to set background on a per-slide or per-deck basis
Removed the context menu
Added the ability to reset the background to the deck default
Added the transparency checkerboard pattern
Fixed various bugs with background color application and preview