Replace the old (and broken) jshint + jscsrc by eslint and configure
it to support some of the ES6 features.
The command `eslint` currently has one error which is a bug that was
discovered by its static analysis and should be fixed (usage of a
dead object).
This new draft saving system is currently only implemented for the
card description and comment. We need better a component
inheritance/composition model to support this for all editable fields.
Fixes#186
* Automatically display the overlay when the card details is opened
(previously we waited for the mouse to enter the card details panel)
* Improve the design of the minicards badges
* Change the minicard background when it is hovered or selected
* Removes unimplemented features links from the UI
* Fix the board canvas position when the sidebar is open (was hidden
behind)
Fixes#215
