Modernize & extend

[sebakerckhof]

This is way bigger than what one PR should contain and you may not want all of these changes, but I just wanted to give back the improvements I've done on the library on our private NPM space.

The major things are:

• Rewritten from commonjs to ES modules
• Added tooling to compile back down (also for testing)
• Changed some linting rules to be more up to date with current best practices
• Upgraded all dependencies to their latest versions (except for xmldom because of: Namespace propagation is no working correctly jindw/xmldom#215 )
• Other ES2017 enhancements such as async/await, object rest/spread etc.
• Replaced all querystring/url handling with the new node 8 URL api (WHATWG URL api)
• Added support for some authentication request options around the context classes (you can now specify the request authentication context classes, the comparison and whether to hide the object in general).
• Fixed some minor bugs

Because of the new URL api and ES features, the minimum compatible version is now node 8.