Merge pull request #3 from pjvds/master

Fix BeNilMatcher not matching nil pointers
added godoc documenation for gomega
Adds FitsTypeMatcher

This matcher is to compare two instances by type.
Prevent panic on comparing nil values
Rename FitTypeOf to BeAssignableTo
Adds godoc documentation to BeAssignableTo
Cleanup unused types and verbose comments
Update specs for AssignableTo matcher