Fixes #9

Support unix sockets for redis in sidekiq
Add schema to resque.yml.example
 Merge branch 'gitlab-org/gitlab-ci#9' into 'master'

Support unix sockets for redis connection in sidekiq

Backward incompatibility regarding config/resque.yml - the schema is required now.
Because of this patch makes it behaving the same way it works in gitlab-ce, I think it is fair enough to handle it here similarly.