Update close button to cancel and disable other close mechanisms
Don't persist changes to selected columns when the user cancels
Use defered rendering when canceling changes

Additionally, I removed the difference check as was not using it
correctly. Since we are doing deffered rendering, I'm going to leave it
rendering everytime unless there is a need to stop it from acting that
way.
Change defer to explicit delay

The current call stack seems to be already clear once when the "Cancel"
is being clicked. An explicit delay allows the modal and backdrop to be
before the revert occurs.
Merge pull request #172 from cbmi/issue-164

Don't persist changes to selected columns when the user cancels