Change session handling

Stop using memcache, use mod_auth_gssapi filesystem based ccaches.
Remove custom session handling, use mod_auth_gssapi and mod_session to
establish and keep a session cookie.
Add loopback to mod_auth_gssapi to do form absed auth and pass back a
valid session cookie.
And now that we do not remove ccaches files to move them to the
memcache, we can avoid the risk of pollutting the filesystem by keeping
a common ccache file for all instances of the same user.

https://fedorahosted.org/freeipa/ticket/5959

Signed-off-by: Simo Sorce <simo@redhat.com>
Reviewed-By: Jan Cholasta <jcholast@redhat.com>

ipapython/cookie.py

@@ -112,7 +112,7 @@ class Cookie(object):
 
     cookie = Cookie('session', session_id,
                     domain=my_domain, path=mypath,
-                    httpOnly=True, secure=True, expires=expiration)
+                    httponly=True, secure=True, expires=expiration)
     headers.append(('Set-Cookie', str(cookie)))