Refactored initialization process. Removed after_init event

+ Minor code refactor
+ Minor code cleanup
+ Add app.shortcode-parser
+ Refactored initialization process
+ Add Application::filterContext(context, callback)
+ Fixed helper partials bug when no helpers present
+ Refactor Helper.sanitize and Helper.sanitize_escape
+ Now escaping brackets and braces on sanititizer helper
+ Updated tests and added new test cases