ImportError: No module named '_pandasujson'

As I mentioned in https://github.com/cloudpipe/cloudpickle/pull/80, a change introduced after 0.2.2 breaks a previously working serialized function call that relied on importing pandas. My suspicion is that serialization of functions that utilize `pandas` may be broken in recent versions of cloudpickle.

Full backtrace from Dask/prep.py:

```
Traceback (most recent call last):
File "prep.py", line 64, in
dask.compute(values)
File "/Users/aron/anaconda3/envs/parallel/lib/python3.5/site-packages/dask/base.py", line 204, in compute
results = get(dsk, keys, **kwargs)
File "/Users/aron/anaconda3/envs/parallel/lib/python3.5/site-packages/dask/multiprocessing.py", line 177, in get
raise_exception=reraise, **kwargs)
File "/Users/aron/anaconda3/envs/parallel/lib/python3.5/site-packages/dask/local.py", line 521, in get_async
raise_exception(exc, tb)
File "/Users/aron/anaconda3/envs/parallel/lib/python3.5/site-packages/dask/compatibility.py", line 59, in reraise
raise exc.with_traceback(tb)
File "/Users/aron/anaconda3/envs/parallel/lib/python3.5/site-packages/dask/local.py", line 289, in execute_task
task, data = loads(task_info)
File "/Users/aron/anaconda3/envs/parallel/lib/python3.5/site-packages/cloudpickle/cloudpickle.py", line 840, in subimport
__import__(name)
ImportError: No module named '_pandasujson'
```