Should support plain serialization

[tfredrich]

GET http://localhost:8081/users threw exception: ResourceException
com.strategicgains.hyperexpress.exception.ResourceException: Cannot create resource for content type: application/json; charset=UTF-8
at com.strategicgains.hyperexpress.DefaultResourceFactory.createResource(DefaultResourceFactory.java:57)
at com.strategicgains.hyperexpress.HyperExpress._createCollectionResource(HyperExpress.java:359)
at com.strategicgains.hyperexpress.HyperExpress.createCollectionResource(HyperExpress.java:196)
at org.restexpress.plugin.hyperexpress.HyperExpressPostprocessor.process(HyperExpressPostprocessor.java:84)