Iss. #57 - Add check to skip validation if there are no new commits

Added Denis to list of usual suspects as this will be going up as the new Gitlab server hook. Adds a skip if there are no new commits to validate. Fixes the _nil message as that comes from the validation API

requested review from @cguindon, @droy, @epoirier, @zhoufang, and @zacharysabourin

approved this merge request

For additional context, here is the results of my testing. Forgot to post when I created issue:

Username for 'http://localhost': root
Password for 'http://root@localhost': 
Enumerating objects: 5, done.
Counting objects: 100% (5/5), done.
Delta compression using up to 8 threads
Compressing objects: 100% (2/2), done.
Writing objects: 100% (3/3), 326 bytes | 326.00 KiB/s, done.
Total 3 (delta 0), reused 0 (delta 0), pack-reused 0
remote: Commit: 1ea434763058c79a2a903269cdecbdee64ad0f41		✔
remote: 
remote: 	Reviewing commit: 1ea434763058c79a2a903269cdecbdee64ad0f41
remote: 	Authored by: Martin Lowe <martin.lowe@eclipse-foundation.org>
remote: 	Eclipse user 'malowe'(author) is not a committer on the project.
remote: 	Eclipse user 'malowe'(author) has a current Eclipse Contributor Agreement (ECA) on file.
remote: 	Eclipse user 'malowe'(committer) is not a committer on the project.
remote: 	Eclipse user 'malowe'(committer) has a current Eclipse Contributor Agreement (ECA) on file.
remote: 
remote: 
To http://localhost/eclipse/dash/dash-gitlab-testing.git
   7b66fa0..1ea4347  HEAD -> malowe/test
branch 'malowe/test' set up to track 'upstream/malowe/test'.
❯ git push upstream test1 -u
error: src refspec test1 does not match any
error: failed to push some refs to 'http://localhost/eclipse/dash/dash-gitlab-testing.git'
❯ git push upstream HEAD:test1
Username for 'http://localhost': root
Password for 'http://root@localhost': 
Total 0 (delta 0), reused 0 (delta 0), pack-reused 0
remote: There are no commits to validate for current push, skipping validation step
remote: 
remote: To create a merge request for test1, visit:
remote:   http://localhost/eclipse/dash/dash-gitlab-testing/-/merge_requests/new?merge_request%5Bsource_branch%5D=test1
remote: 
To http://localhost/eclipse/dash/dash-gitlab-testing.git
   7b66fa0..1ea4347  HEAD -> test1

merged

mentioned in commit 19d9fa5a