Copy boot file as well so we have a backup of it

Makefile

@@ -0,0 +1,4 @@
+copy:
+	ampy --port /dev/ttyUSB0 put code/boot.py
+	ampy --port /dev/ttyUSB0 put code/main.py
+	ampy --port /dev/ttyUSB0 put code/hcsr04.py

code/boot.py

@@ -0,0 +1,7 @@
+# This file is executed on every boot (including wake-boot from deepsleep)
+#import esp
+#esp.osdebug(None)
+import gc
+#import webrepl
+#webrepl.start()
+gc.collect()