Remove unused library code (#153)

This code is for working with the raw wptreport.json format, and isn't
used by any code. Everything is now using the packed Git results.

Author: foolip

lib/index.js

@@ -1,9 +1,7 @@
 'use strict';
 
 const browserSpecific = require('./browser-specific');
-const metrics = require('./metrics');
-const report = require('./report');
 const results = require('./results');
 const runs = require('./runs');
 
-module.exports = { browserSpecific, metrics, report, results, runs };
+module.exports = { browserSpecific, results, runs };