Final tidy up of Comment Style and Validation

Add classes for client side error validation.
Make errors prettier.
Make textarea a more useful size.
Reset the comment area of the form on submit.
Fix show remote errors bug.
JavaScript and styling for post creating/editing

Automatically set pub_data to today when creating.
Add jQueryUI datepicker for pub_date.
Automatically slugify title while editing.
Make title and slug fields wider.