Expanded the functionality of the login button shortcode

A container div is now wrapped around the button/notifications generated by the launchkey_form() function, and that function has been updated to accept the variables $id, $class and $style for formatting the container.

The [launchkey_login] shortcode now accepts the following parameters: "id", "class", "style" and "hide".

"id, class, and style" are backslash escaped and passed through to the updated launchkey_form() function.

The "hide" variable acts as a boolean string and controls the auto-hide functionality of the shortcode.  If "hide" == "true" and a user is already logged in then the login button will not be displayed.