Provide Admin link to existing function which Update Base Directory Path and Base URL for a site

As of 2.0, there is a special "form" which detects what the current settings SHOULD be for Base Directory Path and Base URL for a site. This form provides a way to change these values when a site is moved without clearing the entire config_backend column (i.e. without resetting all the other values stored in that column).

For 2.1 - we'll add an explicit link under the Administer >> Configure menu to users can find / use this feature when needed (generally when a site is moved to another location in the directory system, moved to another server, and / or has it's URL / domain changed).