Transfer filename via Content-Disposition header if files[0] is not a File instance.

This is a workaround for browsers which don't support a filename param
for FormData.append (e.g. Gecko).
Define cross-browser blob slice method as widget method.
Workaround an exception in Gecko when using Blob.prototype.slice as widget property.

The exception thrown was "Illegal operation on WrappedNative prototype
object" and occurs due to the proxying of the jQuery UI widget methods.
Enabled orient_image option by default.
Updated required JavaScript Load Image library to version 1.7.0.
Updated jQuery version.
Fixed JavaScrip Load Image script source.
Retain EXIF and ICC headers with client-side image processing. Closes #1207.

Use Exif data thumbnails if available, which increases UI performance
largely when displaying thumbnails of large image files.