fix inheritance for RESTFeatureTyle getAttribute methods

Conflicts:

	src/main/java/it/geosolutions/geoserver/rest/decoder/RESTFeatureType.java
	src/main/java/it/geosolutions/geoserver/rest/decoder/RESTResource.java
Merge pull request #99 from geosolutions-it/1.5.x-RESTFeatureTypes-attributes

fix inheritance for RESTFeatureTyle getAttribute methods