Added CountsReportsWithIdenticalExceptionType test. Test succeeds.
Separting code into BugreportStats.cs
Added CountsReportsWithIdenticalStackTrace test. Test succeeds.
Refactored BugreportStats.cs to static class.
Refactored and moved code out into separate files.
Created Humbug.Core with IBugreport and BugreportStats classes.
Modified Index.cshtml to list test bugreport counts grouped by exception type.