Merge branch 'release/1.5.0'

* release/1.5.0:
  Do not need to force table reloads after deleting rows/sections
  Make work code and location more generic, fixes hughescr/Timesheets#10
  Allow employees to be deleted: resolved hughescr/Timesheets#8
  Ensure UI updates happen on main thread
  Remove unused property
  Added outlets for add job and delete employee buttons
  Add (hidden) delete button in section header view (not yet hooked up)
  Add delete button image
  Update to newer OSX version/XCode
  64-bit warning fixes