Similar to 
list but recursive and returns only
 primitive values for the file at each location. Guaranteed for
 each path is only the values id and mimetype.
 
 After a call to unwrap, the returned 
RMap for a
 call to treeList("/user_1/dir0") might look something like:
 
 
 
 {
 "/user_1/dir0/file1.txt" :
 {
 "id":10,
 "mimetype":
 "binary",
 "size": 10000L
 },
 
 "/user_1/dir0/dir1" :
 {
 "id": 100,
 "mimetype": "Directory",
 "size": 0L,
 "files":
 {
 "/user_1/dir0/dir1/file1indir.txt" :
 {
 "id": 1,
 "mimetype": "png",
 "size": 500
 }
 }
 }
 }