Summary:
Pull Request resolved: https://github.com/facebookexperimental/eden/pull/67

With this change it will be possible to build dependencies of and run integration tests using getdeps.py.

This is the first goal of Q4 as per https://fb.quip.com/v8YzAYNSYgot: "Get Open Source version of integration tests running on Legocastle".

Before this diff:
The OSS integration tests run now on GitHub by:
- Building some test dependencies with getdeps.py
- Building some test dependencies with homebrew/apt-get
- Running tests via python script

The OSS integration tests were not running on Sandcastle.

After this diff:
The OSS integration tests run on Github by:
- Building and executing tests via getdeps.py (execution of tests happens by getdeps.py calling Make calling python script)

The OSS integration tests run on Sandcastle using the same getdeps.py setup as Github.

Reviewed By: krallin

Differential Revision: D24253268

fbshipit-source-id: cae249b72d076222673b8bbe4ec21866dcdbb253