Proper validation of "Repo by URL" parameter

Sorry if this is a duplicate but I could not find a similar issue. I see this locally and on gitlab.com

Just put some git@... link and try to import projectScreen_Shot_2017-05-30_at_16.01.41Screen_Shot_2017-05-30_at_16.02.27

/cc @smcgivern @markglenfletcher

Edited by Valery Sizov