[Reviewer Andy] Dynamic Sproutlet loading

Andy

Can you review the changes for dynamic sproutlet loading.  I'll email updated spec separately.

Mike
Some of them are there because S-CSCF function hasn't fully moved to the sproutlet yet (this covers the reg_store objects, and the scscf_acr_factory).  On the others, there is an interesting question about how much we should share objects between sproutlets and how much we should separate them, for example ...

-  Both S-CSCF and I-CSCF now can do ENUM look-ups, so should they share one EnumService object or should they instantiate separate ones?  I'm not 100% sure the c-ares library will work if we instantiate separate ones.
-  Ditto for HSSConnection?  If we separate them then we will have more HTTP connections between each Sprout node and the Homestead cluster.
-  Should we have separate ralf connections for each sproutlet or should they all share the same one.  Again, this will effect the number of HTTP connections between each Sprout and the Ralf cluster.
-   The HttpResolver is only in the list because it is needed by the XDMConnection object which is only constructed by the MMTEL AS Sproutlet.

My gut feel is we should look at implementing some form of centralized service registry as part of the API to clean this up.