Make it so that enqueue_scripts is no longer a special case

It now behaves using its hook name rather than using a special function name

Signed-off-by: Jeremy Massel <jeremy@ignitionmedia.ca>
Use more obvious code

Signed-off-by: Jeremy Massel <jeremy@ignitionmedia.ca>
only register the style if the file exists on the server

Signed-off-by: Jeremy Massel <jeremy@ignitionmedia.ca>