Cmis.io.save needs to be passed a filename parameter.

It is a pain to extract the fliename from a nsIRUI and we need the
filename for the download manager and the save notification.
Added nsIFilePicker.filterAll to promptpath.
Removed overwriteAction check from Cmis.utils.buildpath to Cmis.utils.target.

This enables the overwriteAction check to be preformed on a 'Save As'
quicksave action.
s/var/let/g
Moved 'Generate Menu' button below the 'Separator' button.
s/Generate Menu/Generate/
Make sure to check return from Cmis.utils.target.