If a limit is specified, we have to make sure the value is a string before trying to limit it, otherwise the code fails if the value is not a string (e.g. an integer).
jquery.sortable.js is now needed by quarantine.js
Added everything needed to get the spam score out of the database and be able to sort on it (or any other data presented to the user).
Added support for sorting the table that is shown to the user.
Specify a default order in the default URL.
Perform the sorting at the SQL level instead of Python.
Reimplemented Quarantine on the basis of Listing.
Merge branch 'master' into feature/score-and-sorting-in-quarantine

Conflicts:
	modoboa/extensions/amavis/views.py
wip: sort spam messages by score.

Better navigation parameters storing. We don't use the same places
to store webmail and quarantine parameters anymore.

see #375
wip: sort spam messages by score.

Code improvement.

see #375
wip: filter messages by type.

Initial work.

see #376
Unicode conversion would fail if the data was a string encoded with utf-8.
Merge branch 'master' into feature/score-and-sorting-in-quarantine

Conflicts:
	modoboa/extensions/amavis/lib.py
	modoboa/extensions/amavis/views.py
	modoboa/extensions/webmail/lib.py
	modoboa/extensions/webmail/views.py
Include all paremeters when building the url.

see #375
Merge branch 'feature/score-and-sorting-in-quarantine' of https://github.com/tonioo/modoboa into feature/score-and-sorting-in-quarantine
Merge branch 'master' into feature/score-and-sorting-in-quarantine
A simple user can now see all its quarantined messages.

fixes #89
Few fixes.

see #89
More intuitive message selection.
Merge branch 'master' into feature/score-and-sorting-in-quarantine

Conflicts:
	modoboa/extensions/amavis/views.py