Simple CI for the users

Summary:
Add a button on a repo that will:

• Create Jenkins pipline job
• Harbormaster build plan
• Herald commit rule

Configure the Application by adding this to conf/custom/myconfig.conf.php

'jenkins.url' => 'https://scitassrv18.epfl.ch/jenkins/',
'jenkins.user' => 'admin',
'jenkins.token' => 'token_from_jenkins',
'jenkins.repo_cred' => 'admin_creds_for_c4science', // id of jenkins credentials

for repo_cred, create a credential on jenkins with the c4science admin user information, so jenkins can access all repositories.

Test Plan:

• Go to a repo
• Have a Jenkinsfile
• Click the button
• Check that there's a job on Jenkins Blue

Maniphest Tasks: T1245, T632, T882

Differential Revision: https://c4science.ch/D147