Cascading Data Gap Recovery Requests

[ritchiecarroll]

As an example, if a down-stream historian is connected to a data source via GEP that supports data gap recovery for its remote data sources, it would be nice if the historian could make a data-gap recovery request by-proxy to its data source.

This way if the historian needs to restart it can request the missing data from its primary data sources.

[ritchiecarroll]

Code complete. Needs testing.