ws: Remove authentication from the websocket

After this change all websocket communication is authenticated,
authentication is handled at the HTTP level.

This commit may need tweaks to detect expired cookies appropriately,
and indicate to the user to reauthenticate.
ws: Support Kerberos authentication via GSSAPI

This is just basic support. The authentication is not yet passed
on to other servers.
ws: Add option to override kerberos keytab path