#206 - Set class loader for dummy method proxies.

The Enhancer used to create the proxy instances wasn't explicitly
setting the class loader to use, which meant by default the proxied
class's class loader was chosen. This is fine for controller classes, but
in some containers the return types for the controller may have a
class loader that doesn't have access to Spring, resulting in
ClassNotFoundExceptions. For example, returning a JAX-RS class JBoss.
Using the controller's class loader when proxying the return type solves
this. 

Related issues: #136.
#202 - Prepare 0.14.0.RELEASE.
#202 - Release version 0.14.0.RELEASE.
#202 - Prepare next development iteration.
Use a LinkBuilderFactory in ResourceAssemblerSupport.

ResourceAssemblerSupport used static calls to
ControllerLinkBuilderFactory to create links. Add ability to pass in a
LinkBuilderFactory instead to customize how links are created, for
example to work with JAXRS. Default to existing behaviour for existing
constructor.

Add method support to JaxRsLinkBuilder.

Pulled out some common code into LinkBuilderSupport, and added necessary
methods to JaxRsLinkBuilder + Factory to support linking to
controller/service methods.