ref(*): Manage test dependencies using godeps

Simplify test running and dependency management.

Follow deis coding standards
> Use of third-party go packages should be minimal, but when doing so,
vendor code into the Deis package with the godep tool.
fix(tests): destroy without --app flag to remove git remote
Merge pull request #2743 from mboersma/fix-apps-destroy-test

fix(tests): destroy without --app flag to remove git remote
docs(*): use https:// URL for ci.deis.io
Merge pull request #2738 from mboersma/ci-to-https

docs(*): use https:// URL for ci.deis.io
Merge pull request #2577 from johanneswuerbach/godep-tests

ref(*): Manage test dependencies using godeps
ref(builder): use bash-style substitution

This is already in use at check-repos, which is a fancier way of
stripping the file extension from a string.