Modernize ELT, kill bower and enable yarn

[buschtoens]

Adressing #430.

☠️ bower.json

• 533f6df: Update ember-cli to 2.13, reconfigure to use npm & ember-source instead of bower
• f964cb0: Faker / Pretender shouldn't be needed in bower.json as those are brought in by ember-cli-mirage https://github.com/offirgolan/ember-light-table/blob/master/bower.json
• 4761317: font-awesome should be a devDependency when we move it to the package.json
• a9154f2: Kill bower.json

Also

• 533f6df: Enable yarn
• 84abf5b: Remove jquery@2 from bower.json
• 275b2a9: Upgrade demo to use bootstrap@3.3.7
• 533f6df: Switch from jshint to eslint
• 73490a9: document font-awesome usage, so it's no surprise that the ascending and descending icons don't work when users drag and drop our code snippets, if they don't have font-awesome, and haven't copied our setup.
• fd32329: replace ember-suave with the spiritual successor eslint-plugin-ember-suave
  • 3d47c1c: configure sensibly and fix new linter errors
• 47d98d9: circumvent "Uncaught ReferenceError: this hasn't been initialised - super() hasn't been called at _possibleConstructorReturn" When extending a singleton babel/babel#5862
• 6d38976: Update all other dependencies

Likely out of scope

• Properly set up targets or includePolyfill, so that Demo doesn't work in IE11 #427 gets fixed. Was already broken prior to this PR.

[alexander-alvarez]

technically we only need font-awesome (e.g. via a CDN), do we care to highlight the difference?

[buschtoens]

Oh, yeah. Good catch.

  {{!--
    In order for `fa-sort-asc` and `fa-sort-desc` icons to work,
    you need to have ember-font-awesome installed or manually include
    the font-awesome assets, e.g. via a CDN.
  --}}

Would that be better?

[buschtoens]

In accordance with #438 (comment) this might be better as well?

  /**
   * CSS classes to be applied to an `<i class="lt-sort-icon></i>` tag that is
   * inserted into the column's `<th>` element.
   *
   * For instance, if you have installed `ember-font-awesome` or include the
   * `font-awesome` assets manually (e.g. via a CDN), you can set
   * `iconAscending` to `'fa fa-sort-asc'`, which would yield this markup:
   * `<i class="lt-sort-icon fa fa-sort-asc"></i>`
   *
   * @property iconAscending
   * @type {String}
   * @default ''
   */

[alexander-alvarez]

in lieu of having documentation that explains what icon fonts are & how they work (I couldn't find anything on the web), this well explained documentation with an example will do 👍

[buschtoens]

Thanks for reviewing! 😃