REL-2056: observation queue broken

This is an emergency fix in order to start the December (2015A Semester) testing cycle.  I made a mistake when working on combining Activators and getting the WDBA included in the ODB back in May.  The problem is that a new `SessionManagement` object is created with each new request.  The `SessionManagement` object contains the queue of observations so even a newly queued observation will not appear when requested until this update is applied.  The reason this is more complicated than it should be is that XML RPC requires a no-argument constructor for the handler classes and creates them via reflection.  You just register them as a handler using the class itself:

        mapping.addHandler(ISessionXmlRpc.NAME,  SessionXmlRpcHandler.class);

Note that unfortunately I'm branching from an out-of-date `develop` because I haven't updated to 1.7 yet.  This change is small enough though that I don't anticipate any problems.