Ensure AVAILABLE_LANGUAGES is a list (close #272).
Fixed Indonesian translation field and ForeignKey field name clash.

The official ISO-639-1 code for Indonesia is "id"; replaced this
problematic suffix with the ISO-639-2 3-letter code in the translation
field names (http://en.wikipedia.org/wiki/Indonesian_language).
Add __reduce__ to MultilingualQuerySet (ref #273).
Merge pull request #275 from wrwrwr/fix/indonesian

Fix support for Indonesian language ('_id' language suffix).
Get language getting from the field attribute rather than name.

The method seems to be not used anymore, but fix it nevertheless.
Added flake8 config to tox.ini.
Merge pull request #278 from wrwrwr/feature/flake8-config

Include flake8 config in tox.ini.
Let's check if flake8 in travis can read parameters from tox.ini.
Set TabbedTranslationAdmin class depending on Django version. Added a new class for Django 1.5 which depends on older jquery/jquery-ui versions. Updated the jquery/jquery-ui versions for the existing admin classes (ref #270).
Update deprecated imports with Django >= 1.7
Merge pull request #283 from amarandon/master

Update deprecated imports with Django >= 1.7
Made sync_translation_fields command respect the verbosity option.
Refactored sync_translation_fields for better readability.
Made it possible to run sync/update_translation_fields limited to models
from a single app.

There is a new command line option "--app" for both commands that takes
an app label. You can also directly pass an AppConfig or a pre-1.7 app
(models module) as a call_command argument, which is handy when executing
the commands as part of a post_migrate/syncdb handler.
Coded a test for sync_translation_field.

The DirtyRegistryTestBase restores the registry after each test, unlike
TestAutodiscover that did it only after the whole test case was finished.
This is needed for test_update_command if it happens to run after
sync_update_command, but should also make autodiscovery tests more robust.