Add ability to create database as subtree of existing tree This patch adds the ability to create a subsystem that uses an existing subtree to create the internal basedn. This is useful for instance, for IPA which will use the original o=ipaca as the top level DN for a KRA, which will be situated at o=ipadrm, o=ipaca. The patch also allows such a system to be cloned, but not to setup the replication agreements, on the assumption that the data is already being replicated at the top-level DN or some higher level. The patch also contains some minor cleanups - removing unused imports and removal of an invalid reference in the python code. Ticket 1051 Note: Changes to the man pages will be submitted in a separate follow-on patch. Please review, Ade