Refs #11112. Modified the property TimeInterval.

Such that it can take a list of doubles instead of 1.

-	modified:   ../Mantid/Framework/Algorithms/src/GenerateEventsFilter.cpp
-	modified:   ../Mantid/Framework/Algorithms/test/GenerateEventsFilterTest.h

-	modified:   ../Mantid/Framework/Kernel/src/InternetHelper.cpp:
	the cast of osstringstream to osstream on mac osx.  Modify it
	only to make the compiling pass.