Now using macaddr datatype and added test for adding devices and displaynames

migrations/3_values.sql

@@ -3,7 +3,7 @@ CREATE TABLE Values (
     timestamp TIMESTAMP NOT NULL,
     value FLOAT NOT NULL,
     value_id INT NOT NULL,
-    device_id CHAR(32) NOT NULL,
+    device_id MACADDR NOT NULL,
     active_errors INT NOT NULL,
     FOREIGN KEY (device_id) REFERENCES Devices(ID)
 );