If using= not specified, act on all LDAP servers.

This is in line with what clients expect.

Also means transaction middleware won't die if there are no LDAP
servers.
Fix transaction middleware for using=None
Fix error in looping databases.
Delete a copy and paste error.
Documentation. WIP.
Setup python path for docs.
Add requirements file.
Add django to requirements.
Kludge for readthedocs.

python-ldap won't build on readthedocs as it is missing the ldap header
files.
Remove obsolete function.
Make rdn_to_dn a private function.
Updates to documentation.
Mock smbpasswd too.
Add python-django to build depends.

Required to generation documentation.
Version 0.2.13.
Also clean docs/_build directory.