Feature/python3.2

[tkem]

Resolves issue phihag/ipaddress#15

• Add from __future__ import unicode_literals to both ipaddress.py and test_ipaddress.py.
• Replace all Unicode string literals, i.e. u'...' and u"..." with plain string literals.
• Replace string literals used in struct.pack() and struct.unpack() with byte literals for Python 2.6 compatibility.
• Add Python 3.2 support to .travis.yml and setup.py classifiers.
• All unit tests passing for Python 2.6, 2.7, 3.2 and 3.3; see https://travis-ci.org/tkem/ipaddress.
• Bump ipaddress.__version__ to 1.0.6, the version used in setup.py; if you release a new version, don't forget to update the version number in both files, or better, rewrite setup.py to use the version from the module.

[phihag]

Thank you very much! Merged.