FIX: select-kit refactoring

- improve mini-tag-chooser keyboard behavior
- all multil select now respond to select all and left/right arrows
- improve events handling
- many minor tweaks

test/javascripts/components/category-selector-test.js.es6

@@ -72,6 +72,7 @@ componentTest('interactions', {
       assert.equal(this.get('categories').length, 3);
     });
 
+    this.get('subject').expand();
     this.get('subject').keyboard().backspace();
     this.get('subject').keyboard().backspace();