Issue 36: Collection handling and deserializers for JSON-HAL

According to the spec and the mailing list, collections of resources are supposed to be serialized in the "_embedded" property with relations.

This pull request does the following:
* serialize instances of Resources<T> in this fashion using the "content" relation. Currently there is no specific logic to "find" a specific relation.
* add deserializers for JSON-HAL for ResourceSupport and Resources
* add serialization and deserialization tests

A piece of Information about the deserializers: currently the only way for a deserializer to figure out the content type of a Resources<T> instance is by evaluating the Jackson BeanProperty. This type resolution is not perfect as it does not handle other available sources of Type information (Jackson annotations on interfaces for example)
See: https://github.com/FasterXML/jackson-databind/issues/165

Should fix  #36