Repo URL containing a ":" with no port number causes failed SSH Agent reg to fail

Issue
When entering a repository URL with a colon, but accidentally omitting the port number, e.g. http://mirror.hortonworks.local:/hdp/HDP-2.2.0.0 instead of http://mirror.hortonworks.local:8080/hdp/HDP-2.2.0.0 the following behavior is observed:

1. Repo validation passes

2. Agent SSH bootstrap passes

3. Installation fails

4. When going back to the "Select Stack" and fixing the issue, validation succeeds as expected
5. Agent SSH bootstrap fails due to HDP.repo and HDP-UTILS.repo being malformed due to the missing port number.

6. User is stuck unless they manually remove all HDP.repo and HDP-UTILS.repo files from the server

See attached screenshot flow for each step.

This is a valid Base url. Passes validation in Ambari UI and works just fine...

http://public-repo-1.hortonworks.com/HDP/centos6/2.x/GA/2.2.0.0

This is also a valid Base url. Passes validation in Ambari UI BUT yum chokes... so it's not until we get past Deploy and start trying to use the .repo that yum fails...

http://public-repo-1.hortonworks.com:/HDP/centos6/2.x/GA/2.2.0.0

Proposed Solution: expanded URL validation should be implemented during repository validation to prevent malformed but workable (depending on the tool) URL's to be propegated.