Slideshow1 comments clarification

Just a change in the comments.  New themes are not required to include
slideshoww.css or controls if they do not want to customize, because
they will be pulled from the plugin folder if absent.
Merge pull request #841 from gjr-osweb/master

Slideshow1 comments clarification
Merge remote-tracking branch 'upstream/master' into upstream0719

Conflicts:
	zp-core/zp-extensions/slideshow.php

	modified:   zp-core/zp-extensions/slideshow.php