Handle missing HTTP method and version gracefully (trac #4352). #159

I've attempted to fix http://dev.piwik.org/trac/ticket/4352 myself by making the HTTP method and versions (the spaces surrounding them, really) optional. With this patch, I was able to import a few hundred of our sites.

Feel free to cherry pick any/all of it and adjust the style.

Thanks for PR. Can you rebase on the latest master, then we can see if the code works (if Travis is green then your PR should mostly work). Also will be nice if you can add a test case showing the wrong input data in eg. https://github.com/piwik/piwik/blob/master/tests/resources/access-logs/fake_logs.log (at the end)

See: http://dev.piwik.org/trac/ticket/4352