Add git-url + build button

The Build Button will only appear if Status is 'InProgress' and a git-url
is provided

- When editing or creating a new package, the git-url format will be verified
- Addition of a 'wrapper build' field to specify if build is a wrapper build or
  a chain build
- Pressing the Build button will submit a PUT to our mead-scheduler website, and
  using the return code as an indication, the appropriate message will be shown
  to the user.
- Use of AJAX for submitting builds!

TODO:
- Right now the prod is hardcoded to 'eap6'. Eventually when we will use this
  feature with eap5, we'd like to find a better solution.
-