Temporarily disabled Module tests due to MESOS-1942.
Escaped JSON object keys.

All strings in JSON need to be escaped, including the keys in
dictionaries / objects.

Review: https://reviews.apache.org/r/26723
Refactored stout os open/close/fcntl.

Review: https://reviews.apache.org/r/26843
Updated verify_reviews.py to use the git pre-commit hook.

Review: https://reviews.apache.org/r/26798
Renamed verify-reviews.py to verify_reviews.py.
Fixed default port values for master and slave in the documentation.

Review: https://reviews.apache.org/r/26254