Add node.states() to the client library

The node.states() does issue GET request at /nodes/<uuid>/states to get
the current states of that node.

Change-Id: I9e93447df53a0ba1e0f723e95af80fb126218626
Remove tox locale overrides

* tox.ini: The LANG, LANGUAGE and LC_ALL environment overrides were
introduced originally during the testr migration in an attempt to be
conservative about the possibility that locale settings in the
calling environment could cause consistency problems for test runs.
In actuality, this should be unnecessary and any place where it does
cause issues ought to be considered an actual bug. Also, having
these in the configuration actively causes older pip to have
problems with non-ASCII content in some package metadata files under
Python 3, so drop it now.

Change-Id: Id761060cd974772749a82c42217647428e631324
Closes-Bug: #1277495
Fix Iterface misspelling from node-validate cmd

The result from a node-validate cmd includes a table with
'Iterface' as one of the headings. This changes it to 'Interface'.

Change-Id: Iac28d3c65f56ee6cd77f4611db0e513b1b9b008b
Merge "Remove tox locale overrides"
Merge "Add node.states() to the client library"