Address Deprecation Warning #175
Description
Our tests uses a schema feature that is considered deprecated for Python 3+ with the following warning:
"/home/travis/virtualenv/python3.4.8/lib/python3.4/site-packages/jsonschema/validators.py:928: DeprecationWarning: The metaschema specified by $schema was not found. Using the latest draft to validate, but this will raise an error in the future.
cls = validator_for(schema)
Checking for JSON code in /home/travis/build/openworm/tracker-commons/WCON_format.md
Testing JSON code snippet 1 from /home/travis/build/openworm/tracker-commons/WCON_format.md"
This should probably be fixed by the next release.