wakatime 2.1.6 (new formula)

Adding new formula for wakatime
It won't install without both `ENV["PYTHONPATH"] = libexec+"lib/python2.7/site-packages"` and `ENV.prepend_create_path "PYTHONPATH", prefix+"lib/python2.7/site-packages"` but I removed `ENV.prepend_create_path "PYTHONPATH", libexec+"lib/python2.7/site-packages"` and it still installs.