Bug 15684: Fix encoding issues with quote upload

Bug 15684: Fix encoding issues with quote upload

To verify:
- Download attachment 'Goethe with umlaut' from Bug 15684
- Go to Tools > Quote Editor
- Click "Import quotes" and select the file
- The quotes display in a table. Click 'Sav quotes'
- Result: Nothing happens

To test:
- Apply patch
- Repeat steps above
- Verify that you get a message '2 quotes saved' and that the quotes
  are added in to the quotes table
- Test with attachment 'sample quotes' as well

Signed-off-by: Mirko Tietgen <mirko@abunchofthings.net>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Brendan Gallagher brendan@bywatersolutions.com
(cherry picked from commit 59fc32531071e3d4594a8b5555acd41a17921de3)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>