Switch from MySQL-python to PyMySQL
Switch from MySQL-python to PyMySQL

As discussed in the Liberty Design Summit "Moving apps to Python 3"
cross-project workshop, the way forward in the near future is to
switch to the pure-python PyMySQL library as a default.

https://etherpad.openstack.org/p/liberty-cross-project-python3

Change-Id: I4fd721d6f27bc0125144d960ee5028ce842a60f8

openstack/api-site,Tesora/tesora-api-site,openstack/api-site,dreamhost/api-site,Tesora/tesora-api-site,dreamhost/api-site,dreamhost/api-site,Tesora/tesora-api-site,dreamhost/api-site,Tesora/tesora-api-site,openstack/api-site,dreamhost/api-site,openstack/api-site,Tesora/tesora-api-site,dreamhost/api-site,dreamhost/api-site,Tesora/tesora-api-site,Tesora/tesora-api-site