Show revision in footer; clean up path and site setup

[drkitty]

Major changes:

• wsgi.py has been moved to the root of the repo.
• You can use a virtualenv even via WSGI. wsgi.py automatically takes care of the details.
• To import Cyder or one of its libraries from a script, do import activate; activate.activate() instead of import manage.

Minor changes:

• The current revision is now displayed in the footer.
• If you use a virtualenv, you no longer need to activate it before running manage.py.
• Some incorrectly duplicated libraries were removed, so we no longer rely on a specific ordering of sys.path.
• To form an absolute path from a relative path from the root of the repo, use cy_path from the activate module.

[murrown]

There's a bit of outdated documentation that references tastypie in cyder/cydns/models.py

[drkitty]

Re: the stuff in cyder/cydns/models.py, I'll take a look at that.

[murrown]

I'm ready to merge this as-is though, the stuff I pointed out was what I considered noteworthy but none of it is deal-breaking. When you think this pull request is ready, I say go ahead and merge it.

[drkitty]

Ready to go.