Improve navigation & structure of documents

Presently, the new RTD contents list in the sidebar is more or less unusable:

https://www.dropbox.com/s/bl36v087cza6r7v/Screenshot%202014-07-14%2014.48.21.png (image)

The new version looks like:

https://www.dropbox.com/s/soiv9iq4vss1v9k/Screenshot%202014-07-14%2014.49.50.png

The expanded table of contents still appears in the main index page.

conf.py has also been updated to use the new RTD theme locally, if the user has it installed; if not
it will use the built-in theme as usual.

Also includes miscellaneous minor corrections.
Backports documentation restructure from develop

Commits:

52a480beec529955cf2ebbd618666520c238ad39
ea6e46ef874a76b9eebd8d7de8db6782f1d01806
Merge pull request #3307 from evildmp/documentation-backport

Restructure documentation and improve contents tables (backport)
Fix docs building
Merge pull request #3313 from yakky/feature/fix_docs_master

Fix docs building on master
Fix location of breadcrumb template in docs

`breadcrumb.html` is actually located in `menu`, not `cms`.
Merge pull request #3369 from derek73/patch-1

Fix location of breadcrumb template in docs
permissions for static placeholder editing
added tests to permissions for static placeholder editing
removed the STATIC_PLACEHOLDER_PERMISSION settings as suggested
Permissions for static placeholders, update

* Renamed is_flat to is_editable
* made render_plugin templatetag aware of the placeholder
* updated the render_plugin function to consider plugin.is_editable
added migration for static placeholder user permissions
moved migration
fixes to errors introduced in rebase
rebase and renamed db migration
Merge branch 'develop' into glomium-static_permissions

Conflicts:
	cms/templatetags/cms_tags.py
fix tests
Merge pull request #3381 from digi604/static_permissions

Static placeholder  permissions rebase
changelog
locales updated