Add site class

src/lib/src/main/java/gov/usgs/earthquake/nshmp/netcdf/www/NetcdfService.java

@@ -198,12 +198,15 @@ public abstract class NetcdfService<T extends Query> {
   }
 
   static class ResponseMetadata {
+    public NehrpSiteClass siteClass;
     public String xLabel;
     public String yLabel;
 
     ResponseMetadata(
+        NehrpSiteClass siteClass,
         String xLabel,
         String yLabel) {
+      this.siteClass = siteClass;
       this.xLabel = xLabel;
       this.yLabel = yLabel;
     }