Remove python-ldap and add pyldap

Keystone moved from python-ldap to pyldap in the Newton release and
python-ldap now requires a version of pyasn1-modules that exceeds
the upper-constraint in Ocata, which breaks repo builds.

This patch removes python-ldap and adds pyldap in its place.

Closes-Bug: 1736241
Change-Id: I55f1fcd928c70eff3488af50d3dddb588082eb43
(cherry picked from commit ffc9c9b)

defaults/main.yml

@@ -427,14 +427,14 @@ keystone_pip_packages:
   - keystonemiddleware
   - ldappool
   - lxml
-  - PyMySQL
   - oslo.log
   - oslo.middleware
   - pbr
   - pycrypto
+  - pyldap
+  - PyMySQL
   - pysaml2
   - python-keystoneclient
-  - python-ldap
   - python-memcached
   - python-openstackclient
   - repoze.lru