Standalone channel usage (closes #84)

- Channel accepts event messages with processor id 0
- Channel accepts plain events
- Standalone channel usage example
- Fix erroneous sequence number recovery with Journal.IO (closes #95)
- Reset temporary sender paths for previously persisted output messages
- Undo temporary changes in ReliableChannelSpec
- Additional tests
  * sequence number recovery
  * sender path reset
Merge pull request #96 from eligosource/wip-84-standalone-channels

Standalone channel usage (closes #84)