optimized imports and final touch-ups

datastore/src/main/java/net/jami/datastore/dao/ContactDao.java

@@ -63,7 +63,7 @@ public class ContactDao extends AbstractDao<Contact> {
                 "VALUES " +
                 "(?, ?, ?)");
             ps = object.getInsert(ps);
-            return ps.execute();
+            return ps.executeUpdate() != 0;
         }
         catch (Exception e){
             log.error("An error has occurred while trying to store a user: " + e.toString());

datastore/src/main/java/net/jami/datastore/dao/DeviceDao.java

@@ -66,7 +66,7 @@ public class DeviceDao extends AbstractDao<Device> {
                     "VALUES " +
                     "(?, ?, ?, ?, ?)");
             ps = object.getInsert(ps);
-            return ps.execute();
+            return ps.executeUpdate() != 0;
         }
         catch (Exception e){
             log.error("An error has occurred while trying to store a user: " + e.toString());

datastore/src/main/java/net/jami/datastore/dao/SystemDao.java

@@ -64,7 +64,7 @@ public class SystemDao extends AbstractDao<SystemAccount> {
                     "VALUES " +
                     "(?, ?, ?)");
             ps = object.getInsert(ps);
-            return ps.execute();
+            return ps.executeUpdate() != 0;
         }
         catch (Exception e){
             log.error("An error has occurred while trying to store a system entity: " + e.toString());

datastore/src/main/java/net/jami/datastore/dao/UserDao.java

@@ -72,7 +72,7 @@ public class UserDao extends AbstractDao<User> {
                     "VALUES " +
                     "(?, ?, ?, ?, ?, ?, ?,?, ?,?, ?)");
             ps = object.getInsert(ps);
-            return ps.execute();
+            return ps.executeUpdate() != 0;
         }
         catch (Exception e){
             log.error("An error has occurred while trying to store a user: " + e.toString());