Merge pull request #13 from travis-ci/sf-set_template_path

Allow the templates_path to be set
Remove worker templates

We now assume that travis-cookbooks is cloned to the same directory
as travis-images
Bypass list_versions command
Inject cookbooks SHA where system_info cookbook expects

For https://github.com/travis-ci/travis-cookbooks/commit/ed0ff5594b7ecf7c8ea51665b0145ebec079af46
and later
Remove dead code
Update default templates_path

The location of the VM templates (YAML Chef run_lists) has changed in
travis-cookbooks repository.

See travis-ci/travis-cookbooks#412
Merge pull request #14 from gildegoma/move-templates_path

Update default templates_path
Change template paths corresponding to https://github.com/travis-ci/travis-cookbooks/commit/3b31398
Merge branch 'master' of github.com:travis-ci/travis-images
split template configs