[MIN] Add flask and werkzeug to requirements
[IMP] Use werkzeug dispatcher middleware
[IMP] Add flask app stub, make it runnable
[IMP] Add .wsgi file for the flask app
[FIX] Use correct Flask root_path

Thanks to indico being a namespace package flask sometimes fails at
determining the package root path correctly
[DEL] Broken/unused htdocs files
[IMP] Add routes for all the old htdocs functions
[IMP] Use request.is_secure and request.remote_addr
[MIN] Remove try..except around werkzeug import

we require it now so it's not necessary anymore
[MIN] Use git versions of flask and werkzeug
[MIN] Remove --flask option (non-flask is broken)

The legacy wsgi app is not usable anymore due to changes to make
everything work with flask. So there's no need to have it accessible
anymore.
[MIN] add absolute_import future
[IMP] Add flask/cache-based sessions

Stored using GenericCache, i.e. in redis, memcached, etc.
[IMP] New session implementation and lots of fixes

- RHs and JSON-RPC are basically working
- API is still broken
- Anything storing non-core data in the session is still broken
[FIX] Fix HTTP API pt. 1

- api works
- oauth and file retrieval still broken
[FIX] Remove AccessWrapper.getSession calls
[FIX] Session usage in logout
[FIX] Session usage for menuStatus

...which is apparently never set btw.
[REF] FileAPI: Hardcoded http status codes
[DEL] test*.py in htdocs