Minor UI enhancement following review.

Redesign Locations view.
Move History button to Browse.
Change backup for "notexists" item.
Merge Last revision and Previous revision columns.
Restrict access to /admin/
Change authentication filter to redirect to /login/.

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.
Correct usage of "title" to be in templates.
Remove obsolete page error.
Correct encoding error in db_sqlite and db_ldap to support username and
password with non-ascii characther.
Enhance ldap search logs.
Add "id" attribute to login form. Will be used as a token for testing.