Resolved problem w/ user button detection. Problem was due to button …

…and USART sharing same GPIO of PA0,PA1. Moved USART to use PA2,PA3.

user/apps/gpioer/main.c

@@ -69,7 +69,7 @@ void *gpioer_thread(void *arg)
     {
 			printf("gpioer thread: built-in leds blinking - count %d\n", count);
             leds_onoff(count++);
-            L4_Sleep(L4_TimePeriod(1000 * 1000));
+            L4_Sleep(L4_TimePeriod(500 * 1000));
     }
 }