SLING-2984 : improve import-content wizard:
 * made it a standard import wizard again (still also accessible via context menu)
 * warnings if project is not added to a server
 * restricting target location choice to a project and the option to change the jcr_root of that project
 * more beautify to come later (not scope of this ticket)

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1508890 13f79535-47bb-0310-9956-ffa450edef68