PEP8: Over-indented continuation lines.
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).
Taught reload_app to clean up translator registry from dangling models.
Refactored the main test base to avoid some module reloading.

There were a couple of issues with the heavy reloading:
* test_update_command could fail due to some non-Model classes in
  tests.models ending up as NoneType (Django 1.7 specific?);
* reloading translator module was creating a new copy of the registry,
  making debugging tests harder;
* setting models and translation to None on the module scope was
  preventing something like "from tests import models" to do what it
  should do.

Note that there is still some reloading and some globals black magic.
To get rid of it completely we'd need to provide unpatching of models
(such that unregistering would be equivalent to not registering).
Cleared importing values from settings into the command modules scope
to avoid having to reload the modules after modeltranslation settings
are changed.
Shortened a couple of translator.translator phrases.
Removed the test_settings.py file and moved the statement to tests.py for
simplicity.

If there is some use for a separate file I'm not aware of this should be
simple to revert.
Limited test_update_command to the modeltranslation.tests models.

This prevents its failure trying to update user-models registered
with languages different than the test languages.
Made test_registration only count models from modeltranslation.tests app.

The only thing that was preventing the test from failing in the context
of a project with its own models registered for translation was the
translator registry duplication, which was removed in 1e566f4e.

The models count change is due to no longer considering the single
registered model from "managed_app".