- overhaul handler interface to make async, eliminate unnecessary
baggage
- modify controller to return no-body 202
- fix docs re postback URL
version bump, clean out unnecessary dependencies
Merge branch 'release/v0.13.0' into develop
add resize_to_fill operation

resolves #1
version bump to 0.13.1
Merge branch 'release/v0.13.1' into develop