[fix] Allow keyboard navigation for non-input fields

fixes uxsolutions#874

Author: gr2m

js/bootstrap-datepicker.js

@@ -397,7 +397,8 @@
 			else {
 				this._events = [
 					[this.element, {
-						click: $.proxy(this.show, this)
+						click: $.proxy(this.show, this),
+						keydown: $.proxy(this.keydown, this)
 					}]
 				];
 			}