Fix #25: Machine-readable output with --json.
Fix #25: Machine-readable output with --json.

Use only the "errors" property of the JSLint output.

The "function" property contains circular references,
which can't be represented in JSON.

BenoitZugmeyer/node-jslint-extractor,BenoitZugmeyer/node-jslint-extractor,marcusoftnet/node-jslint,afischer-sfly/node-jslint