Tests and code coverage

Wampy.js uses mocha and chai for tests and c8/istanbul for code coverage. Wampy sources are mostly all covered with tests! :)

# use standard npm test command
> npm test
# or only some tests
> npm run test:node
> npm run test:node-no-crossbar
> npm run test:browser

# for code coverage report run
> npm run cover
# and then open coverage/lcov-report/index.html