Specify master branch in cf-deployment git resource
Specify master branch in cf-deployment git resource

* since concourse git resource will otherwise default to 'develop'

[#173736483](https://www.pivotaltracker.com/story/show/173736483)

Co-authored-by: Renee Chu <dbb10253d556b7398455fa674afa4c4a5a96979a@vmware.com>

pivotal-cf-experimental/bosh-bootloader,pivotal-cf-experimental/bosh-bootloader