Description of problem:
If:
- a project has not selected to override the server languages (no custom list)
- the server has a language that is not enabled by default,
- the group has added this language

then the project version will show in the group's page with no given warnings, and can attempt to open the document and results in presenting an error to the user.

Version-Release number of selected component (if applicable):
dev

How reproducible:
Moderate, seems always

Steps to Reproduce:
1. Log in as admin, go to Sidebar menu -> Administration -> Manage Languages
   - Ensure there is, in the set of languages shown, one with an unchecked "Enabled" checkbox (ie. disabled by default)

2. Go to Groups, select or create a new group
3. Go to Settings -> Languages
4. Add the "disabled by default" language

5. Go to projects and either
   - create a basic, all defaults project (no overrides)
   - alter an existing one to remove the overrides
6. Add a source document to the project version if none exist

7. Go back to Groups -> the created group
8. Go to Settings -> Projects
9. Add the project version as was created/altered above
10. Click languages
   - See the disabled language is there, but with no warnings
11. Click the language so that it shows the project in the sidebar
12. Click the project name
   - See that it proceeds to a document list
13. Click the document

Actual results:
22/11/13 14:30:34 Failed to load data from server

Expected results:
Should never have got this far - the group page should recognised the disabled by default language and presented an error.

Additional info:
My fingers hurt after typing this bug.