Upgrade apt message if no python-apt to intercept potential user questions.

library/apt

@@ -31,9 +31,7 @@ APT_PATH = "/usr/bin/apt-get"
 APT = "DEBIAN_PRIORITY=critical %s" % APT_PATH
 
 def debug(msg):
-    # ansible ignores stderr, so it's safe to use for debug
     print >>sys.stderr, msg
-    #pass
     
 def exit_json(rc=0, **kwargs):
     print json.dumps(kwargs)
@@ -46,7 +44,7 @@ def fail_json(**kwargs):
 try:
     import apt
 except ImportError:
-    fail_json(msg="could not import apt")
+    fail_json(msg="could not import apt, please install the python-apt package on this host")
 
 def run_apt(command):
     try: