Add product, version and group at the top of the crash report page

Allow showing a group by the uuid of any of it's individual crash This removes the dependency on insertion order. Also split Group::stats_by_product_and_version from get

Cleanup, don't capture group in regex

Allow extra columns in group index, and split search columns

Rename sample config and add more examples

Store client_info in database

Fix race condition in CrashGroup::find_or_create by using constraint and upsert (for pg > 9.5) or table lock