Scanner: Always make sure to try to scan in colors or, if not possible, in Gray

Signed-off-by: Jerome Flesch <jflesch@gmail.com>
Merge branch 'master' of github.com:jflesch/paperwork
Use "is" or "is not" when compare with None

See PEP8 explanation http://www.python.org/dev/peps/pep-0008/#programming-recommendations
Merge pull request #139 from kryskool/patch-1

Use "is" or "is not" when compare with None
README: Fix

Signed-off-by: Jerome Flesch <jflesch@gmail.com>
Merge branch 'master' of github.com:jflesch/paperwork
Backend: Image import: Fix image import.
Temporary fix : Gio is not used anymore.

Signed-off-by: Jerome Flesch <jflesch@gmail.com>
Merge branch 'master' into date-text-change