Display a cancel button if the server-side validation failed. Fixes #2538

Replace label-important with label-danger (Bootstrap 3 change).
Display progress for each file in a file upload request.
Work on a copy of the headers in _initXHRData

If someone passes a "headers" options to fileupload(), this object get overwritten across multiple files upload because the same object is being re-used.
Merge pull request #2550 from rslinckx/patch-1

Work on a copy of the headers in _initXHRData
Refactored last merge and updated version number.
Updated package version.
Check if a context node is given.
Updated package version.
Minor event handler refactoring.
Allow to define the dropEffect and preventDefault handling in the dragover handler. Closes #2557
Use an isolated scope for the fileUpload and fileUploadProgress directives. Closes #2578
Updated version number.
Handle cases where no type is set but the form contains an input field with the name "method". Fixes #2585
Use the + operator instead of array_merge to properly handle numeric keys. Fixes #2589
Use the preview property to store and retrieve the image previews. Fixes #2592
Fixed file upload error handling.

Thanks to Daouda Kanoute for the report.
Added imageOrientation parameter to define the orientation for resized images.
Moved the core file input styling into separate files.
Don't use CSS imports. Closes #2610
Updated Bootstrap Links, Icon info and Gallery version. Closes #2622