#131 - Add Traverson hypermedia client API.

Introduce Traverson as means to traverse hypermedia based APIs by providing a set of relation names to discover and follow to access the final representation. Traverson allows to specify a parameter map that will be used  to potentially expand the URIs discovered.

We currently support LinkDiscoverer based relation discovery, which means that relations in HAL representations can be found by simply stating their names. Alternatively JSON path expressions can be used (starting with a $).
#172 - Made types contained in Link implement Serializable.
#170 - LinkBuilder takes X-Forwarded-Port header into account if present.

ControllerLinkBuilder now inspects the X-Forwarded-Port and uses that if present. If an X-Forwarded-Host header doesn't contain a :, we now also reset the port to prevent the local one from leaking into links generated.
#114 - Support for type mappings on sub-types in ControllerLinkBuilder.

When building links for method invocations we previously only inspected the type that declared the method for type level mappings. We now use the type the method was invoked on explicitly.
#167 - Prepare 0.11.0.RELEASE.

Updated pom.xml. Upgraded to Logback 1.1.2, Jackson 2.3.3, Spring Plugin 1.1.0.
#167 - Updated changelog.
#167 - Release version 0.11.0.RELEASE.
#167 - Prepare next development iteration.
Merge remote-tracking branch 'upstream/master' into useMessageConvertersForResources

Conflicts:
	src/main/java/org/springframework/hateoas/mvc/ControllerLinkBuilder.java