Expanded Fastlane setup + Jenkins integration

[sebalopez]

Description:

• Added test-only lane for CI use
• Minor changes to existing lanes ( ad-hoc releases for internal QA use)
• Jenkinsfiles for CI and Release pipelines
• Expanded README with complete project setup requirements (particularly regarding code signing)

[germanStabile]

Amazing work @sebalopez!

One thing we were discussing with the iOS team is that it may not make sense to incorporate the Jenkins integration to the master branch since this is open source and the implementation seems to be tightly related to Rootstrap workflow.

We were thinking in keeping this in a feature branch were we can base our projects from. What do you think?

That being said I really liked the additions to the fast lane documentation and I think that does belong here.

We can discuss more in slack. Thanks!!

[sebalopez]

after internal discussion, removed the Jenkins setup from this branch, to be kept separately under feature/jenkins