closes #50

print available system info before attempting to load the module.

This activated tab/space mismatch testing, which is now enabled by default.

Why CAS updates get pushed out in the order that they do is unknown by me.
The ordering is clearly fragile, and the tests should not rely on it.

Something changed the ordering in the last year+ of releases of python, EPICS,
etc.  The updated ordering seems stable on my current test setup, producing
no test failures in 60+ runs of the full test suite.

Should still try to figure out a way to make the managers tests not sensitive
to update ordering.

Access of the commit object returns a ValueError if the repo hasn't been
fully initialized yet (no initial commit).

mostly updates for usage of new graph `nodes` View object:

https://networkx.github.io/documentation/stable/release/migration_guide_from_1.x_to_2.0.html

finally using proper packages

This allows for executing the guardian.version module to convert
version strings to/from ints, and to produce a new release version.

closes #30

Was assuming that all managers are NodeManager.  But the system allows
specifying Node objects as well, so we need to support that here
(or disallow).

This was an oversight bug.  Throw connection error, as expected.