refa ParameterModel, add a static factory

src/main/java/org/bench4q/share/models/agent/ParameterModel.java

@@ -26,4 +26,10 @@ public class ParameterModel {
 		this.value = value;
 	}
 
+	public static ParameterModel createParameter(String key, String value) {
+		ParameterModel parameterModel = new ParameterModel();
+		parameterModel.setKey(key);
+		parameterModel.setValue(value);
+		return parameterModel;
+	}
 }