Merge from StoreGate-03-06-16: Make sure old proxy is not freed until after replaceProxy() call. (StoreGate-02-45-01-13)

	* Tagging StoreGate-02-45-01-13.
	* Merge from StoreGate-03-06-16.
	* src/StoreGateSvc.cxx (typeless_overwrite): Make sure old proxy
	isn't freed until after replaceProxy() call.

2015-06-07  scott snyder  <snyder@bnl.gov>

	* Tagging StoreGate-02-45-01-12.
	* StoreGate/StoreGateSvc.icc: Hide BOOST_CONCEPT_ASSERTs from
	clang, to avoid warnings.
	* StoreGate/StoreGateSvc.h, StoreGate/StoreGateSvc.icc: Add
	unique_ptr versions of readPrivateCopy/retrievePrivateCopy.
	* test/SGtests.cxx: Use them.