Make it a noop in Ember > 3.0.0-beta.2

[cibernox]

Closes #18

Would you also output a console warning asking users to just remove the addon?
Also, should it be gt('3.0.0-beta.2'); or gte('3.0.0-beta.2');?

[rwjblue]

should it be gt('3.0.0-beta.2'); or gte('3.0.0-beta.2');?

I think gte would work, but I can't recall if ember-cli-version-checker exposes a .gte 😝

[rwjblue]

Would you also output a console warning asking users to just remove the addon?

This is what I have done in the past, but it makes annoying warnings for addons during ember-try scenarios.

Maybe we can tweak the logic to be:

    this._shouldDisable = true;
    if (emberVersion.lt('3.0.0-beta.2')) {
      this._shouldDisable = false;
    } else if (this.parent === this.project && !process.env.EMBER_TRY_CURRENT_SCENARIO){
      this.ui.writeWarnLine('ember-native-dom-event-dispatcher is not required for Ember 3.0.0-beta.2 and later, please remove from your `package.json`.');
    }

Adding the check for EMBER_TRY_CURRENT_SCENARIO should alleviate some of @Turbo87's prior concerns (RE: ember-polyfills/ember-getowner-polyfill#16)...

[cibernox]

Done. It works pretty well and only outputs once.

[rwjblue]

Merging this, would you mind sending another PR updating the README to explain that this addon is not needed with Ember 3.0?