list Azure Blobs by pattern

With the Python Azure API I would like to query blobs by a pattern.

For example, get all report pdf's (with the Unix style path name pattern expansion):

block_blob_service.list_blobs('mycontainer', '**/reports/*.pdf')

Start with the Python Azure API entry point named in the issue, block_blob_service.list_blobs, and review how blob names are currently filtered or listed. The work is done when callers can pass a Unix-style pattern such as '**/reports/*.pdf' and receive the matching blobs, including nested paths.

Written by the indexing model from the issue text.