CSS bugfixes: Squashed commit of the following:

commit e8a13aa38fd2b025a4e682a0431ba973cf5b70df
Author: David Winslow <cdwinslow@gmail.com>
Date:   Sat May 18 15:19:51 2013 -0400

    Allow user to specify workspace when creating style

commit 43423a1cd6fe48afac46648de41b66bc1b1d227f
Author: David Winslow <cdwinslow@gmail.com>
Date:   Sat May 18 14:52:29 2013 -0400

    Fix updating of openlayers preview when style changes

commit dc7008e4acf76eb2965856de6d296a8f353c43fa
Author: David Winslow <cdwinslow@gmail.com>
Date:   Sat May 18 13:45:54 2013 -0400

    Make CSS demo page aware of workspace-scoped styles
Merge branch 'master' of git://github.com/geoserver/geoserver