Ajout de GET /Transaction + prise en compte des transactions dans GET
/User
	modified:   database/Database.java
	modified:   database/DatabaseManager.java
	modified:   database/mongo/MongoDatabase.java
	modified:   database/mongo/MongoHelper.java
	modified:   database/sql/SQLDatabase.java
	modified:   model/DataBean.java
	modified:   model/LoginManager.java
	modified:   model/Transaction.java
	modified:   servlets/TransactionServlet.java
	modified:   servlets/UserServlet.java
	new file:   utils/ServletUtils.java
	new file:   utils/TransactionsUtils.java