Use gtk.PrintOperation to print files.

Also add a new tab to the printing dialog that will allow the user to
configure the font to be used, among other things.

Curently, the print dialog still supports the reports that are created using
pdfs (maybe we could just open evince for those reports and let the user
print from there)

Change-Id: If951244764e3325d6061ae4c5c34f57221a25f77
Merge "Use gtk.PrintOperation to print files."