Support a way to limit # of operations performed on a FDO connection

[brucedechant]

In order to help with more control over FDO connections and how they are managed it would be nice to have a way to limit the # of operations that could be performed by a FDO connection before it would be automatically released.

This would be supported in a similar way to how we support custom pool sizes for providers.

Example: (Under FeatureServiceProperties)

DataConnectionUseLimit = OSGeo.MySQL:10000

The above would limit the FDO MySQL provider to automatically release a cached FDO connection and create a new cached FDO connection every 10000 operations.