Dsjohnson1

Three mods:  
One allows for subclassing the sessionStore, by deferring initialization of store to initInternal and using store held by base class, if it exists.
The other two address some problems of premature expiration, a likely cause of some existing bug reports, data loss due to overwrite of an updated in-memory session from DB, and scalabilty impacts of a lot more DB access than is needed and a lot more sessions kept in memory than are needed.