Adds vendor/cache to .gitignore
Adds vendor/cache to .gitignore

...not used in production

[#116910101](https://www.pivotaltracker.com/story/show/116910101)

Signed-off-by: Caleb Miles <906dbe5b21c7025e252f807d6724eb4d0fd7fb4c@pivotal.io>

cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release