updating pillow and adding management command to handle CommCareCase-Deleted. 

in our case, we are deleting the doc from ES vs. doing anything else fancy pants. main thing is that the ES index doesn't map doc_type (oops), so removal is the best and only way forward now.
Merge pull request #676 from dimagi/case_delete_es

updating pillow and adding management command to handle CommCareCase-Del...