added update function to example, change build out dir

Author: kikass13

examples/stm32f4_discovery/can_m2515/main.cpp

@@ -68,6 +68,7 @@ class MyTask : modm::pt::Protothread
 				mcp2515.getMessage(message_);
 				MODM_LOG_INFO << "Received message: " << message_.identifier << modm::endl;
 			}
+			mcp2515.update();
 		}
 		PT_END();
 	}

examples/stm32f4_discovery/can_m2515/project.xml

@@ -1,15 +1,14 @@
 <library>
   <extends>modm:disco-f407vg</extends>
   <options>
-    <option name="modm:build:build.path">../../../build/stm32f4_discovery/spi</option>
+    <option name="modm:build:build.path">../../../build/stm32f4_discovery/mcp2515</option>
   </options>
   <modules>
     <module>modm:platform:gpio</module>
     <module>modm:platform:spi.bitbang</module>
     <module>modm:platform:spi:2</module>
     <module>modm:build:scons</module>
 
-
     <module>modm:processing:protothread</module>
     <module>modm:processing:timer</module>
     <module>modm:driver:mcp2515</module>