Merge pull request #1288 from mdboom/unit/handle_exceptions_in_parser

Another unreadable VO table: unit parsing failure
Merge pull request #1098 from mdboom/misc/travis-test-with-ascii

Set locale to C on Travis
Merge pull request #1290 from mdboom/misc/cleanup-toplevel-namespace

Cleanup the top-level astropy namespace
Allow for "whitelisting" some packages as not requireing 2to3
Include six.py in extern
Add compatibility wrapper for urlopen functionality
Refactor io.votable to not require 2to3.
Fixes for Python 3.2