Cleanup: Move local TM population to upgrade machinery

This ammends commit ad3210af42
API: Add filtering by code to LanguageResource

This allows to use the Pootle API to check if a given language code returns
any match, and thus to test if some language exists.
API: Include a proper backlink in ProjectResource

Necessary for Pootle-Solas integration.

always_return_data indicates that all HTTP methods (except DELETE) should
return a serialized form of the data.
API: Allow superusers to see all UserResource objects

This will keep hiding certain fields for all the UserResources that don't
belong to the user making the query, thus providing a certain level of
security.
API: Allow to GET UserResource lists in specific cases

Do not show any object when performing a GET request unless an exact filter
on 'username' is provided.

This allows to keep a restricted control on what the API UserResource exposes
to the outside, while making it possible for certain users (superusers) to
check if a given user exists using the Pootle API.
API: Send password reset email when creating new user

This uses a custom template in order to use a different email message for the
users whose account was automatically created using the Pootle API.
Add management command for assigning permissions

This command allows to set permissions for any user on any project, language
or translation project.
Avoid naming clashes
Fix typo
Avoid naming clashes in option values
Create local TM when running initdb management command

This way we get a local TM when deploying from scratch.
Revert "Bundle wikipedia.js into editor bundle"

This reverts commit 80bd1021e3fdf09b5f71e2cde817132a4482a163.
Force caching of MT and Lookup backend JavaScript files

Adding 'cache:true' to Jquery Ajax request to ensure that JavaScript are cached properly. The default behaviour here is adding '?_=[TIMESTAMP]' to forces the browser not to cache the JavaScript files.
Identify newly-modified filter names

Names were previously adjusted in 31cd573.
Bump up minimum required Django version
Cleanups
Provide a more helpful message
Cleanup: Move form and formset from pootle_project views.py to forms.py

This helps to keep view code simpler.
Cleanup: Remove unnecessary extra blank lines