pycurl: add pycurl version to `pycurl.version` and user-agent.

Signed-off-by: Oskari Saarenmaa <os@ohmu.fi>
Spell pycurl the same way it was spelled before
Check that the correct user agent is sent
Merge pull request #47 from p-push/pycurl-version

pycurl: add pycurl version to `pycurl.version` and user-agent.