Chef updates for the dev Vagrant box

WIP
Things to do here:
- [x] Update to Chef 11 using omnibus
- [x] Deal with some dependency management changes
- [x] Use https to fetch cookbooks, as not everyone uses GitHub with SSH
- [x] Update the RVM JSON to install Ruby (Due to changes in JSON interpretation by the cookbook)
- [x] Update cookbook dependencies
- [ ] Pull SIPp from the latest master for @bklang's wonderful new features/changes