add public field to repoconfig schema
Merge branch 'master' of github.com:Strider-CD/strider
if a repo is marked as public, let anonymous users see the the job and
build output pages.

changes:

- require_resource_read middleware now understands public repos.
- jobs routes no longer require authentication, only resource read
  privs.
- jobs pages don't look up the repo config object through the user
  schema (ie not req.user.get_repo_config) but instead have their own
  lookup function which works without a currently logged in user.

bugfix:
- favicon was crashing job detail page due to objectid case. we detect and
  ignore non-object id types.