Websocket adapter for use with ember-cli-remote-inspector

**Still WIP but ready for first feedback**

Closes #235 - VERY related to https://github.com/joostdevries/ember-cli-remote-inspector

#### Added a websocket adapter to both the inspector and ember-debug.
This adapter uses a global called `remoteDebugSocket` which is set by the ember-cli-remote-debug addon.

#### Added a `_disconnect` method to the adapter
Needed to cleanup when changing what app to inspect. This is called right before `app.reset`

#### Added build tasks + dist for websocket version
By doing this, `ember-cli-remote-inspector` can just list the latest version from ember inspector as a dependency and work from there.

Not done (yet):
- Tests
- Documentation
Unfortunately this will break Ember Inspector compatibility with old Ember versions (the `on` method was added later to Ember).  You will need to use the `willDestroy` callback.