subclassed Slideshows into Marquee so that we have a designated banner/marquee template
expanded Slideshows and their variants with the following
-be able to toggle specific ExtraFields
-activate an Orientation setting to lock in a slideshow's dimensions
-be able to pass custom classes into slideshows for separation of stylesheets
-added an Alt tag to the slideshow's extra fields
Merge branch 'master' of http://github.com/punkave/apostrophe