[javascript] Fixed database functions result which were not parsed

nodejs/database/agents.js

@@ -12,5 +12,5 @@ export function getAgent() {
 	if (data === undefined) {
 		return null;
 	}
-	return data.data;
+	return JSON.parse(data.data);
 }

nodejs/database/contracts.js

@@ -9,7 +9,7 @@ export function getContract(id) {
 	if (data === undefined) {
 		return null;
 	}
-	return data.data;
+	return JSON.parse(data.data);
 }
 
 export function setContract(data) {

nodejs/database/surveys.js

@@ -10,7 +10,8 @@ export function deleteExpired() {
 
 export function get(symbol) {
 	deleteExpired();
-	return getSurveysStatement.all(symbol);
+	const data = getSurveysStatement.all(symbol);
+	return data.map(elt => JSON.parse(elt.data));
 }
 
 export function set(survey) {