usage of typing.Deque breaks compatibility

[anselor]

The new TableCreator uses typing.Dequeue, which was added in Python 3.5.4. We currently declare we support 3.5.0 and higher. Debian Stretch maxes out python3 support at Python 3.5.3 so we currently don't support Debian Stretch users and we don't support the versions of python we're currently publishing.

Suggestions:

• We should probably have one of the test variations run on the oldest version we say we support so this gets caught in the future.
• Until we drop support for Python 3.5, we can change the type declaration to be by string.

[anselor]

Ok, it looks like support for earlier 3.5.x python versions must have been broken for a while.