For the /api to work properly with ajax call, we need to support session
cookie in basic auth.

Patrik Dufresne authored Mar 01, 2017 and Patrik Dufresne committed Jan 20, 2018

Replace the /ajax endpoint by /api.

Revisit usage of RdiffError, Warning > RdiffWarning and ValueError >
RdiffWarning. To properly handle all of them.

To simplify the login/logout, assemble all the handling of form
authentication into a single cherry tool. 
This new tools support the following feature:
- handle the session
- validate credential
- show login form when not login
- redirect to original page
- setup the `cherrypy.serving.request.login` with user object

Make use of UserObject everywhere.

Ran `futurize --write --nobackups --stage1 --unicode-literals`

To benefit from cherrypy encoding,decoding,gzip filters. We need to make
the login page a page controller. This also fixes encoding issue if the
login page contains any non-ascii character.