After cloning the repo locally and importing into Eclipse, you want to add ECF and org.restlet to you target platform.
The org.restlet as well as org.restlet.ext.* dependencies can be download from the official restlet website . They provide a p2 repository too  (make sure to grab >=2.2). ECF announces its current p2 repositories on its website . As the time of writing, 3.5.6  is current.