Darwin-py

* Bug fix for importing complex RLE masks from coco.
* Removes extra prints during imports.
* Updated readme with links to documentation.

* Import coco bounding boxes

Features:

* Support for .dcm and .avi files
* Pull video frames instead of video with `-video-frames` flag
* Can now import Darwin JSON videos annotations
* Bug fixes with regards to team-slug/dataset-slug access
* Handle complex polygons in import
* Support for coco complex (RLE) polygons for import
* Better Error handling for unsupported filetypes
* Client can now send delete events

Features:
* Coco export includes bounding boxes
* Support to upload tags to videos with new importer `csv_tags_video`
* removed pycocotool dependency
* Flag to download images into folders `--folders`

Bug fixes
* pulling an export of a different format than darwin json now gives a proper error message

Breaking change
`--as-video` has been removed and instead there is a new flag `--frames` that is the inverse