autotest: remove APM references

Tools/autotest/README

@@ -1 +1 @@
-This is an automated test suite for APM
+This is an automated test suite for ArduPilot

Tools/autotest/autotest.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 """
-APM automatic test suite.
+ArduPilot automatic test suite.
 
 Andrew Tridgell, October 2011
 

Tools/autotest/rover.py

@@ -219,7 +219,7 @@ class AutoTestRover(AutoTest):
     #
     #     # reduce throttle
     #     self.mavproxy.send('rc 3 1500\n')
-    #     self.mavproxy.expect('APM: Failsafe ended')
+    #     self.mavproxy.expect('AP: Failsafe ended')
     #     self.mavproxy.send('switch 2\n')  # manual mode
     #     self.wait_heartbeat()
     #     self.wait_mode('MANUAL')