Compatibility for WebTest 2.0

[peritus]

webtest 2.0 is out, this version doesn't work with robotframework-httplibrary: http://webtest.readthedocs.org/en/latest/changelog.html#id1

However, from the changelog:

Added wsgiproxy support to do HTTP request to an URL [gawel]

.. so maybe we can switch to WebTest 2.0 and remove the dependency on livetest.

[peritus]

Error looks like this:

The last error was: AttributeError: 'TestApp' object has no attribute 'cookiejar'