To build a dismissal alert -
Add a basic alert by creating a wrapper <div> and adding a class of .alert and one of the four contextual classes (e.g., .alert-success, .alert-info, .alert-warning, .alert-danger).
Also add optional .alert-dismissable to the above <div> class.
Add a close button.
Use the <button> element with the data-dismiss = "alert" data attribute.
