Make dict.keys() PY3 compatible
Make dict.keys() PY3 compatible

The dict.keys()[0] will raise a TypeError in PY3,
as dict.keys() doesn't return a list any more in PY3
but a view of list.

Change-Id: Id9c7d3725c01bd0a193d8fc6705443efe9c25c34
Partially implements: blueprint trove-python3
Closes-Bug: #1583419

openstack/python-troveclient,Tesora/tesora-python-troveclient,openstack/python-troveclient,Tesora/tesora-python-troveclient