use remote request on post pin link
use remote link on unpin link
added js destroy view to replace post pin link on unpin action
added validations to pin model
added partial for js errors
added helper method for displaying js errors
removed alert from js errors partial
append error messages to existing jsError element if present
use js_errors to display errors in js format for pin create and destroy actions
use existing .flash for js error messages
styling for alert flash message
styling for show/hide link on flash messages
fixed links for closing/opening alert flash messages
just remove current flash element when displaying js errors
run timeoutFlashMessage function on flash link initialize