This commit fixes the "Payload thrown at incorrect API_PATH"
test, it uses the proper way to check async error throws,
taken from ava.js docs. Done with the aim to increase the
coverage and to ensure working tests. Added "transform-runtime"
to .babelrc to enable "await/async" syntax".
Part of https://github.com/bigchaindb/js-bigchaindb-driver/issues/220
* new command: npm run doc, for generating the API.md file
* new command: npm run dev, for live watching webpack
* JSdoc: make all methods public by default, selectively make some private
* JSdoc: organize all methods under their class
* linting fixes
* package updates