fix bug where accesstoken was never cached. I added to a testcase to check if the accesstoken was being cached, but it was a different instance each time, so I fixed AbstractAuthenticationClient#get_access_token to correctly cache the token, and only refresh upon expiry. new testcase now passes.
Update pom, fix annotations, misspellings. Make tests runnable from any directory (specifying full paths for config files).
address comments: raise_base_request_error -> raise_bad_request_error, Cask Data -> Cask Data, Inc., commandline -> command-line.
Merge pull request #32 from caskdata/feature/misc-fixes

Feature/misc fixes