refactored plugin loaded to initialize plugins in the order given to loadPlugins()

This assures that widgetBar items always appear in the same order.
updated 'remotestorage' and 'hello' plugins to reflect change to dspace.plugin()
added 'widgetBarElement' hook to allow adding arbitrary views / elements to the widget bar.
removed deprecated WidgetBar markup from index.html / index.tmpl
fixed dspace.plugins list, used by views.
moved 'search' feature to plugin