wakatime 2.1.6 (new formula)

Adding new formula for wakatime
Does this need `requests`? That's not in the standard library, is it? wakatime doesn't declare a dependency on `requests` in setup.py. If it needs requests, requests should be vendored into libexec/vendor (like how dependencies are vendored in `jrnl.rb`) and you should update your setup.py. :) If it doesn't, nevermind!