Changed logging to use glog library.

Also fixed versioning and added check for test image existence when running integration tests.
What I'd like to see still, is the possibility to redirect docker stderr & stdout to logger, as well as forcing glog to spit everything to stdout and not stderr as it is right now.

@csrwng @bparees comments welcome.
It's generally bad practice to use any kind of print functions when testing. I switched it to use test log functionality, this way you can easily enable/disable it w/ `-v` flag passed to tests.