LSNBLDR-208 - rearrange dialogs where there are choices to URL, upload or pick; change dialog open/close flow & positioning, style blocks being edited via dialog, avoid opening several dialogs in standard and alternate rendering

git-svn-id: https://source.sakaiproject.org/svn/lessonbuilder/branches/LSNBLDR-208@121854 66ffb92e-73f9-0310-93c1-f5514f145a0a