Updated AggregateRootMappedByConventionTests.cs

OnEventForPrivateMethod(EventForPrivateMethod) was marked as "private
virtual". Private methods cannot be virtual.
Updated AggregateRootMappedByExpressionTests.cs

OnEventForPrivateMethod(EventForPrivateMethod) was marked as "private
virtual". Private methods cannot be virtual.
Merge pull request #104 from theBoringCoder/master

Corrected Two Tests