Swagr Codegen: Updates to generate comments properly for return type of void and for allowed values, other minor updates

code-gen/src/main/java/com/wordnik/codegen/resource/EndpointOperation.java

@@ -299,7 +299,6 @@ public class EndpointOperation {
 			method.setMethodType(this.getHttpMethod());
 			
 			//get return value
-			//private String returnValue;
 			List<Response> response = this.getResponse();
 
 			method.setReturnValue(config.getDataTypeMapper().getReturnValueType(response.get(0).getValueType()));

code-gen/src/main/java/com/wordnik/codegen/resource/ModelField.java

@@ -99,8 +99,10 @@ public class ModelField {
         for(String allowedValue: this.allowableValues){
             result += (allowedValue +",");
         }
-
-        return result.substring(0, result.length());
+        if(result.length() == 0)
+            return null;
+        else
+            return result.substring(0, result.length() - 1);
     }
 
     public void setAllowedValues(String csvAlowedValue) {