Mapping bash, sh, and shell to Generic script type

plus specs!

Closes travis-ci/travis-ci#2856
Closes travis-ci/travis-ci#1201
Switching language map spec to be positive test

per feedback (and JUSTICE)
Merge pull request #306 from travis-ci/db-feature-generic-aliases

Mapping bash, sh, and shell to Generic script type
Remove CouchDB hack

Build images should no longer start CouchDB on boot, so we remove this ugly hack.