Merge pull request #1117 from rfw/fix_fs_slot_processing

Skip processing slots only if the slot is newer and the date is newer.
Merge pull request #1118 from rfw/fix_typo_in_hbase

Fix a typo in in new_crashes.
Merge pull request #1119 from rfw/fix_typo_in_hbase

Rename variables to be less confusing in hb.crashstorage.
Merge pull request #1120 from rfw/stringify_dates_hbase

Stringify dates in the processed_crash dict instead of default.