Re-instrument after document changed.
Delete instrumentation cache when document is deleted.
use call() for better performance

call() performance twice as better than apply()

http://jsperf.com/call-apply-segu
Use ViewUtils.getFileEntryDisplay() on creating new file

On creation of a file item, make sure we use
ViewUtils.getFileEntryDisplay() to set the right extension styles.
Adding Handlebars file extension .hbs to use html syntax
adding the longer extension model for handlebars
Remove 'deleted' handler.
adding handlebars extensions to test
Merge pull request #3657 from adobe/glenn/issue-3652

Re-instrument HTML after document changed
Merge pull request #3699 from tcarlsen/master

Adding Handlebars file extension .hbs to use html syntax
Merge pull request #3690 from rajeshsegu/extension

Issue #3679 - File extension now dimmed if created via File > New