this commit changes the behavior of ipfs add -w:

- it makes it able to work with ipfs add -r <dir>
- instead of hacking around the add, we simply just add a wrapper
  directory around the whole result of the add. this means that
  ipfs add -w calls will output _two_ lines, but this is actually
  more correct than outputting one line, as two objects were added.
  this _may_ break scripts out there which expect the output to
  look a certain way. we should consider whether the old output is
  more _useful_ (even if less in-line with the model.)

License: MIT
Signed-off-by: Juan Batiz-Benet <juan@benet.ai>