Updating Room.cs to use occurrences instead of dealing with events.  Also created multiple CacheToSimple functions, each doing their own thing
Adding the linqpad script I used to try and debug the cache issue
Changing the use of DateTime to SystemTime
Adding stubs for each of the SystemTime.Nows, so we're runing the tests from the expected time
Creating another BusyTimes that take take the perspective of the time in the future (with default being today).  Also updated one test to call BusyTimes in a more sane matter (From Time, To Time).