1.49.0

Refactor

• push table names down into DynamoStorage (750c00ff)
• split SendThenWait into 2 states (155b9fc0)

Features

• emit metrics for any failed notif conversions (4a50700f, closes #33)
• log the nack code in metrics (b795566d, closes #34)
• add dockerflow requirements (13c0fffc, closes #29)
• update dependencies (f7ded753, closes #25)

Bug Fixes

• typo and image link fix (903e46d8)
• drop users with too many stored messages (86c65cae, closes #25)