Serializer support for programmatic inclusion and exclusion on maps

Adding tests for serializer support for programmatic inclusion and exclusion on maps (issue #836).
[In this discussion][1], @garcia-jj suggests to use [Exclusions class][2] to check if the field has to be serialized, but it is just for SkipSerialization annotation and this PR is not for that.

Could we use [reflectField(...)][3] from Serializee for this? What do you suggest?



[1]: https://groups.google.com/d/msg/caelum-vraptor/zEI0fMapOoE/X90LLLTZ-h8J
[2]: https://github.com/caelum/vraptor4/blob/master/vraptor-core/src/main/java/br/com/caelum/vraptor/serialization/gson/Exclusions.java#L47
[3]: https://github.com/caelum/vraptor4/blob/master/vraptor-core/src/main/java/br/com/caelum/vraptor/serialization/Serializee.java#L156
I think this method already works fine, but tests fail because the order of elements into String `expectedResult `.