Infrastructure to run custom Python scripts

According to the following bug https://bugs.launchpad.net/fuel/+bug/1349380, we need a service to run simple Python scripts. These scripts should be implemented to production environment without long-term worklow (It means without packaging of scripts, without writting puppet-manifests for them and other such things).

Common parts of this system are:
- Jenkins master;
- Jenkins slave to run scripts;
- A repository to store sources of the code.
- A repository to store sources of the Jenkins jobs.

Simple example of workflow for this service:
1. Writting of the script(s)
2. Creating of request to add script(s) to the "tools/jenkins-app-engine" (as example) repository.
3. Creating of jenkins job using JJB
4. Creating of request to add new jenkins job to repository.
5. Submiting to the DevOps-team credentials which used in script(s).
6. Finishing of review procedure and merge of new script and jenkins job to the repositories.
7. Implementing of new script(s) to production.

Feature Lead: Andrey Nikitin
Mandatory Design Reviewers: Igor Shishkin, Aleksandra Fedorova
Developers: Andrey Nikitin, Igor Shishkin, Aleksandra Fedorova
QA: Mike Scherbakov