Added multiple pages for manage system
Added content to AdminEmail

Added email text and preview fields with submit button
Updated all manage system pages

GIA, Sabbatical, and SummerResearch Approval/Denial letters, emial
templates, and deadlines
Manage system dropdown tab

Added a dropdown tab which contains links for manage system pages.
Merge pull request #37 from 3olcin/master

Completed overlays
Merge pull request #38 from tehcurrent/master

Updated manage system pages