Handle port numbers in image URI
Handle port numbers in image URI

Summary:
Make sure that the port separator colon is not mistaken as the tag
separator in a docker image URI.

Reviewers: ciera

Reviewed By: ciera

Differential Revision: https://phabricator-dot-shipshapecode.appspot.com/D60

google/shipshape,google/shipshape,google/shipshape,google/shipshape,google/shipshape,google/shipshape,google/shipshape