Add LDAP authentication to Drupal

[tmitchell]

• enabled ldapauth module, entered settings
• hobu tweaked and it is now working
• users who already had a 'local' drupal account don't end up auth'ing against ldap, only users who try to log into drupal without already having an account get passed to ldap. Basically if drupal internal login fails, it bumps the request to ldap.
• outstanding decisions required for how to implement and best use ldap integration - drupal can also read in ldap groups and use them as 'roles' in drupal (i.e. access control roles). Also it can be set up to read/write user attributes through drupal.
• need to also test whether creating a new account will allow it to be created in ldap