[PLAT-4947] fixed registering agianst concrete class
[PLAT-4947] added accessor method for all delegates.
[PLAT-4947] added Delegating and DynamicDelegating ConfigMasters. The former allows splitting a request across a set of config masters; the latter allows dynamic registration of in memory masters at runtime.
[PLAT-4947] DelegatingPortfolioMaster splits requests across a set of underlying masters.
Merge branch 'topic/dynamic_masters'