When running `gomock` to generate mocks in the boulder-tools image there is a requirement on `github.com/golang/mock/mockgen/model` but only during runtime (it is not required to build `gomock`). So that we don't require users to `go get` this package so that it exists in their GOPATH we need to vendor it so that it is always in the GOPATH of the boulder-tools image. In order to vendor this package (since it isn't actually used anywhere) we need to add a special file that imports this package and uses it for a variable that isn't actually used anywhere so that we can satisfy `godep`, this is done in the `test` package.
Fixes#2751.
Roland Bracewell Shoemaker