This is a rebuild/make sync for charms to pickup the fix in charmhelpers to fix
any inadvertant accesses of ['ca'] in the relation data before it is available
from vault in the certificates relation. Fix in charmhelpers is in [1].
Add libpq-dev to bindep.txt for psycopg2-binary module as wheel no
longer exists for py36.
[1] https://github.com/juju/charm-helpers/pull/830
Closes-Bug: #2028683
Change-Id: I2235468188dadd1861c6b22f3424411ecb2f51cd
8c3bf040ab