Parse 'template' value of GitHub /setup endpoint

- Allows Hubot or other clients to specify a template name instead
of relying on matching either the job name or the default
- /setup route response now contains job_config_path
- Updated docs
Merge branch 'master' into template
add this back so #127 is clean against master
store job template in the database
Merge pull request #178 from github/template

Accept custom job template parameter, store in the database