Implement Sass for Admin CSS
Fix Component prototype leak

* Prototype properties defined as objects are shared across all instances
* Update: Events and Status properties are initialized as `null` so that instance properties are independent of other instances (Closes #6)
* Update: Component status is initialized upon first use
* Fix: Conditional check in `Component.get_status()`
* Fix: Use local variable to represent `this` in callbacks
Merge branch 'opt_group_nav' into develop
Audit label text for i18n
Merge branch 'audit_labels' into develop