refactor code to serve staches
add spec for serving homepage
handle images that 404
handle missing image hosts
handle unsupported image formats
remove irrelevant comment re: stache_arg
create named before filter
handle download timeouts
handle generic timeouts
log rekognition errors
check for valid src URLs
refactor Rekognition response getting
handle rekognition api failures
better rekognition error message
Merge pull request #39 from afeld/error-handling

better error handling