Added mmr and olc to the OpenLDAP backend provisioning-scripts

Added mmr and olc to the OpenLDAP backend provisioning-scripts

These extensions add mmr (multi-master-replication) and olc
(openldap-online-configuration) capabilities to the
provisioning-scripts (provision-backend and provision.py), for use
with the openldap-backend (only versions >=2.4.15!).

Changes / additions made to the provision-backend  -script:
added new command-line-options:
--ol-mmr-urls=<list of whitespace separated ldap-urls> for use with mmr
(can be combined with --ol-olc=yes),
--ol-olc=[yes/no] (activate automatic conversion from static slapd.conf
to olc),
--ol-slaptest=<path to slaptest binary> (needed in conjunction with
--ol-olc=yes)

Changes / additions made to the provision.py -script: added
extensions, that will automatically generate the chosen mmr and/or olc
setup for the openldap backend, according to the to chosen parameters
set in the provision-backend script

Signed-off-by: Andrew Bartlett <abartlet@samba.org>