Always allow anonymous read of public repository over HTTP

If the project is not public or if the request is a push then "Git Smart
HTTP" must be set to "HTTPS and HTTP" or the request must be over HTTPS.

* app/controllers/git_http_controller.rb
  (GitHttpController#authenticate): Check for disabled repository and
  allow anonymous read for non push requests over either protocol.
Add missing parentheses in if with an assignment
Merge pull request #29 from baby-gnu/hotfix/allow-anonymous-read-over-http

Always allow anonymous read of public repository over HTTP
Thank you!