Fix obsoleted import name
Fix parse_version() to parse webassets_version
Imporve tox and Travis configuration

* Both use requirements-dev.pip.
* Now tox tests with latest Flask and {py26,py27,pypy} .
* Now Travis tests with Flask {0.8,0.9.0.10} and {py26,py27,pypy}.
Merge pull request #48 from papaeye/improve-tox-travis

Imporve tox and Travis configuration

Conflicts:
	.travis.yml
	setup.py
	tox.ini