Summary:
Notable changes since 0.5.0

* Added `below snapshot` command to save historical data to a single file that can be used with `replay` and `dump` commands
* Added btrfs view to track top files by disk space on btrfs filesystem
* New zoom functionality from process view to cgroup view
* Improvements to dump (add TSV format, multi-value field option)
* Sort by selected column (e.g. cmdline) instead of always sorting by the index column (e.g. comm in Process View)
* Various bug fixes

Reviewed By: lnyng

Differential Revision: D39313600

fbshipit-source-id: 9e4a847305375b9e2f609f08651837f36be2ce1f