Saving, closing, and validation implemented

Settings HTML
- save and cancel buttons updated with ng-click directive to call respective settings controller methods, save button also using ng-disabled with condition of $invalid on the form
- help button updated with current user documentation for spreadsheet gadget (will likely change in future PR)
- removing unused settings alert div
- applying validation logic to spreadsheet controls directive
Merge pull request #22 from stulees/master

Saving, closing, and validation implemented