Upgrade to mocha v3, remove install warnings & errors #3088
Description
When you install wct or the Polymer CLI, you get the following errors:
npm WARN deprecated [email protected]: Please update to minimatch 3.0.2 or higher to avoid a RegExp DoS issue
npm WARN deprecated [email protected]: to-iso-string has been deprecated, use @segment/to-iso-string instead.
npm WARN deprecated [email protected]: Jade has been renamed to pug, please install the latest version of pug instead of jade
npm WARN deprecated [email protected]: Please update to minimatch 3.0.2 or higher to avoid a RegExp DoS issue
the last 3 of these all come from Mocha v2.x.x. Mocha has moved on to v3, where all of these warnings have been fixed. The update seems non-breaking for wct, however it may be breaking for our users if they were relying on weird behavior in their tests. See mochajs/mocha#2350 for details.
How does everyone feel about preparing a new WCT major release, with a version bump up to Mocha v3 and any other breaking changes we've been waiting on?