added vim tempfiles to gitignore
initial token model and unit test
let's use safe ids instead of the default couch ones

Couch uses partly random partly sequential ids by default. We could
change that in couch config to be all random. But this is probably more
safe.
return token on successful login via api
adopting tests to new behavior
Merge pull request #40 from azul/feature/token-auth

Token auth with a database of it's own