Long conversion

This change is part of the proposed changes to address(ServiceStack/ServiceStack.Redis#147). The issue is that Redis can potentially return longs for any integer value, and our code should try to handle that.

Please note that this pull request also depends on a pull request to the ServiceStack project(https://github.com/ServiceStack/ServiceStack/pull/696), since that's where the interfaces are defined.

Note that this will be a breaking change for anyone that is actually using the int responses.

Dan