Convert recipe examples to includes

Makes it much easier to test things - no copying'n'pasting just run the
examples straight from the dir (after wiring stuff up)

docs/examples/led_travis.py

@@ -0,0 +1,19 @@
+from travispy import TravisPy
+from gpiozero import LED
+from gpiozero.tools import negated
+from time import sleep
+from signal import pause
+
+def build_passed(repo='RPi-Distro/python-gpiozero', delay=3600):
+    t = TravisPy()
+    r = t.repo(repo)
+    while True:
+        yield r.last_build_state == 'passed'
+        sleep(delay) # Sleep an hour before hitting travis again
+
+red = LED(12)
+green = LED(16)
+
+red.source = negated(green.values)
+green.source = build_passed()
+pause()