Drop `go get -t` from Travis config
Drop `go get -t` from Travis config

This is no longer needed now that we vendor, also drop the corresponding TODO.

Signed-off-by: Ian Campbell <a8db091655a7f47ecb9c39a2d278e9662e440dc0@docker.com>

stevvooe/continuity,containerd/continuity,stevvooe/continuity