Use package name as namspace is discouraged

Flask now recommend naming packages flask_foo instead of the now
deprecated flaskext.foo. Flask 0.8 introduces a redirect import system
that lets uses import from flask.ext.foo and it will try flask_foo first
and if that fails flaskext.foo.

Using the flaskext namespace turned out to be problematic in practice
because many different competing namespace package systems exist and pip
would automatically switch between different systems and this caused a
lot of problems for users.

Text from:
http://flask.pocoo.org/docs/extensiondev/#extension-import-transition

Usage:
from flask.ext.lesscss import lesscss
lesscss(app)