Support Python3.4.

Append py34 to tox and travis configurations according to travis-ci update.

See also:
http://blog.travis-ci.com/2014-04-28-upcoming-build-environment-updates/

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
Merge pull request #24 from mkouhei/support_py34

Support Python3.4.