Add a resetPagination method to the searchable mixin

Searchable can be used without pagination, but reseting pagination
is more a function of search than pagination insofar as if you
add search to a page, you are also going to want automatic pagination
resetting.

ui/app/mixins/searchable.js

@@ -36,6 +36,16 @@ export default Mixin.create({
   fuzzySearchEnabled: false,
   regexEnabled: true,
 
+  // Search should reset pagination. Not every instance of
+  // search will be paired with pagination, but it's still
+  // preferable to generalize this rather than risking it being
+  // forgotten on a single page.
+  resetPagination() {
+    if (this.get('currentPage') != null) {
+      this.set('currentPage', 1);
+    }
+  },
+
   fuse: computed('listToSearch.[]', 'fuzzySearchProps.[]', function() {
     return new Fuse(this.get('listToSearch'), {
       shouldSort: true,