Skip processing slots only if the slot is newer and the date is newer.
Merge pull request #1117 from rfw/fix_fs_slot_processing

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

Fix a typo in in new_crashes.
Rename variables to be less confusing in hb.crashstorage.
Merge pull request #1119 from rfw/fix_typo_in_hbase

Rename variables to be less confusing in hb.crashstorage.
Stringify dates in the processed_crash dict instead of default.

HBase needs the dates in string form in other places as well, so it not
only affects the JSON dumps but also the timestamps in HBase column
mutations.
Merge pull request #1120 from rfw/stringify_dates_hbase

Stringify dates in the processed_crash dict instead of default.