Added IValidateEntity w/ concrete implementation

This will abstract out the extension methods and allow you to program to
an interface.  The concrete implementation just calls the
ValidateEntityExtensions methods
Merge branch 'master' of https://github.com/jefferydutra/EntityAndValueObjectBase

Conflicts:
	EntityAndValueObjectBase/EntityAndValueObjectBase.sln.DotSettings.user
	EntityAndValueObjectBase/EntityAndValueObjectBase.v11.suo