Recursive delete and create node(s)

*ensure_path(), similar to "mkdir -p"

*delete(): combining _delete() (single node deletion) and _rdelete()
 (recursive deletion), which is similar to "rm -r"

*add test case test_basic

*modified basic and acl in examples/ for demoing
Merge pull request #4 from changbl/working

Recursive delete and create node(s)