Prep Plugin for release on WordPress.org (#23)

* Update translation text domain
* Escape everything that should be escaped.
* Add nonce checks where needed.
* Sanitize all inputs.
* Apply Code style changes across the codebase.
* Correct many deprecation notices.
* Optimize load order of many filters.
* Add Proper Build script
* Use emojii flags
* Fix i18n deprecation  notice for translating too early
* Put all scripts in footer and load async

views/legacy/signup/pricing-table/pricing-table.php

@@ -60,7 +60,7 @@ $accent_color_2 = wu_color($accent_color->darken(4));
  */
 if ( ! isset($is_shortcode) || ! $is_shortcode || $atts['show_selector']) {
 	wu_get_template('/legacy/signup/pricing-table/frequency-selector');
-} // end if;
+}
 
 /**
  * Displays error message if there are no plans
@@ -103,7 +103,7 @@ if (empty($plans)) {
 					'current_plan' => $current_plan,
 				]
 			);
-		} // end foreach;
+		}
 
 		?>