fix for firefox blob -> array buffer and back again

Here's a first crack at fixing the bug in firefox when uploading files.   This converts the file blob into an array buffer, and then on the receiving end turns it back into a blob.

I'll be honest I started working with the source code today, but couldn't get `grunt-source --server` running.  I keep getting `Fatal error: listen EACCES` so I couldn't run any of the tests, so I have no idea if this is breaking other functionality.  In my project all seems to be going well so far.