(uDuf) Prevent unsaved dialogue appearing when no changes made on FileUpload

[barryokane]

Addresses this issue in media section (U4-9996) and content (U4-7484)

Three things changed:

• FileUpload has a hidden field for 'fileCount' which is updated in controller & this was causing the issue : added no-dirty-check attribute
• Changed the no-dirty-check directive so the instead of relying on 'onFocus' event to override dirty value it is always false (also should avoid confusion if setPristine is ever called) : see http://issues.umbraco.org/issue/U4-4902#comment=67-43816 and https://stackoverflow.com/questions/17089090/prevent-input-from-setting-form-dirty-angularjs
• Explicitly call $setDirty in fileupload Angular controller when a fileSelected event is fired.

[barryokane]

PR was started at Uduf ;)

[robert-cpl]

Code looks good and it works, awesome work @barryokane :D.