godeps doesn't get everything we want, so fix the problem but write it
to a parallel tree since _workspace is reserved only for godeps auto-generated
files.
- Add Godeps/LICENSES.md
- Add verify-godep-licenses to verify that Godeps/LICENSES.md is up to date
- Trigger verify-godep-licenses in the pre-commit hook only if the Godeps dir has changed
- Exclude verify-godep-licenses in verify-all
- Add verify-godep-licenses to make verify (used by travis)
- Add verify-godep-licenses to shippable
- Update dev docs to mention update-godep-licenses
Tim Hockin