* adaptive rewrite improvements:
- Add 'application/vnd.apple.mpegurl' as HLS type in rules.yaml and default_rewriter.py
- Support setting max resolution and max bandwidth to choose, defaults to 480x854 and 200000 respectively
- LiveWebLoader provides a get_custom_metadata for specifying WARC-JSON-Metadata header, per mime type (TODO: support customization via rules)
- When filtering, first limiting by resolution (if set), then by bandwidth (if set), otherwise default to max bandwidth
- Max resoluton/max bandwidth stored in WARC record under WARC-JSON-Metadata as 'adaptive_max_resolution' and 'adaptive_max_bandwidth' to ensure replayability. If absent, choose absolute max in manifest to be backwards compatible
- Add sample HLS and DASH manifests for testing, with and without max resolution/bandwidth settings.
