Replaced Python test suite with Node.js test suite

[gaurav]

Currently, we use a Python library (phyx2owl) to convert PHYX files into JSON-LD files that are then tested using JPhyloRef. This PR replaces that with the phyx.js Javascript library to handle this conversion, allowing us to use the same PHYX library for both the Curation Tool and the Clade Ontology.

Specifically, it:

• Replaces the Python test suite with a Mocha-based test suite in Node.js.
• Updated JPhyloRef.jar with an updated development version that includes a JSON-LD reasoner and the ability to read an ontology on STDIN. (Should be replaced by a full version release before this PR is complete)
• Moved existing Python test suite into a 'tests.py' directory with a README explaining that it is deprecated.
• Added a README to phyx2owl to explain that it is deprecated.
• Update main README.md to describe the new test infrastructure.

Ready for review. Should be merged after PR #50.

[hlapp]

BTW if it's deprecated we can move the phyx2owl/ tool into its own repository and then leave it there and remove it here for good. For demonstration, I've created and populated it (using the extract from git filter-branch --subdirectory-filter) here: https://github.com/phyloref/phyx2owl

[gaurav]

Thanks for the git filter-branch, Hilmar! I've opened an issue for deleting the phyx2owl subdirectory from this repository at #51. I'll merge this PR now, and then do the deletion in a separate PR so we're not trying to do too much in one PR.