implement pipeline alternative to test and push

• initiate build based on pull request: push from GitHub vs pull from Jenkins
• provide multiple "build status" on pull request (allow/ease the parallelization of distinct builds, with distinct durations)
• initiate code driven ci using jenkins pipeline

As a developer:

• I want to customize the CI (specific needs for integrating my code)
• I want the CI to provide the fastest feedback as possible on my PRs (for instance: initiate a full build at the time I'm requesting a pull)
• I want the CI to consolidate my pull request with the other repositories (see clone.py branch and fallback branch)
• I want the CI to provide me build statuses as much and as soon as possible
• I want the CI to provide me a detailed view (logs) about the build steps

As a reviewer

• I want the CI to prevent from regression based on thresholds with comparison to the base branch (aka parent branch)
• I want the CI to handle everything that can be automated, in order to focus on human analysis (formatting, code quality, line returns...)

As a branch maintainer, CI manager

• I want to enforce some parts of the build (not the whole Jenkinsfile can/must be customizable)
• I want to ease the pipeline usage by providing in-house pipeline libraries (custom pre-configured steps)

Our system integration points are

• GitHub web-hooks
• Captain Hooks
• Jenkins