Summary:
Created a containerized environment to run unit and integration tests for both javascript and android as well as a Jenkinsfile using the new 2.0 Pipeline syntax for integration into a Jenkins CI cluster.

Here is a quick summary of the changes:

* The android image is built from two separate dockerfiles. There is a base image that handles the heavy lifting of dependencies that are infrequently changed while the secondary image extends the base and allows for much quicker incremental builds on code updates.
* The javascript image is simple and is relatively quick to build, therefore there is no base image for any react specific javascript dependencies and it is all packaged in a single docker image.
* A new `scripts/docker` has been created including some javascript files and shell scripts to aid in the running of the tests
* The instrumentation test runner script can be passed various flags to control which tests run since the entire suite takes a significant amount of time to run synchronously
* Jen
Closes https://github.com/facebook/react-native/pull/11902

Differential Revision: D4609238

Pulled By: ericvicenti

fbshipit-source-id: a317f3ac3be898180b009254a9604ca7d579a8b9