Remove events

[alexcjohnson]

Closes #88 Pretty simple in this repo - components already have n_clicks matching the click event, the only one provided here, so there's really no concern about removing it. Note that rebuilding was done using an updated version of dash, in its own no-events branch (which I haven't published yet). But I did a few other little things while I was in here:

• Added a shortcut to run the tests from npm run test https://github.com/plotly/dash-html-components/commit/173510e86e2ea6d1f0b0af0a13bc9b4942152c82 - unless I'm missing something and there already is an easy way to run them all?
• There were lots of duplicates in elements.txt - I sorted and deduped them https://github.com/plotly/dash-html-components/commit/2f873daa3382be0ecde01c96effc89765e276e8f
• A little linting

[Marc-Andre-Rivet]

Please create the master -> release-v1 merge after this.