fix(ember): import flatpickr styles

Author: c0rydoras

ember/app/styles/app.scss

@@ -7,6 +7,9 @@
 /* ember-power-select */
 @import "ember-power-select";
 
+/* flatpickr */
+@import "flatpickr/dist/flatpickr";
+
 /* Responsive Layout */
 @import "responsive";