remove st and switch to using send

- st is having issues with cutting byes from the end of
  requests, unfortunately, where send is not
- this changes every part of the api and is totally
  breaking, but thats what semver is for!
- add a couple more tests for more thorough coverage
more thorough tests, coverage boosted to 100%
Merge pull request #2 from carrot/remove-st

Remove st