test/TestRunner.py now executes false with no directory prefix

as it is /bin/false on many systems but /usr/bin/false on OS X
test/playbook1.yml now just does command true, rather than command /bin/true,
again so that it works on OS X

Changed from using which false to just using command false to
make it simpler and also match how playbook1.yml works

test/playbook1.yml

@@ -18,10 +18,10 @@
   tasks:
 
   - name: test basic success command
-    action: command /bin/true
+    action: command true
 
   - name: test basic success command 2
-    action: command /bin/true
+    action: command true
 
   - name: test basic shell, plus two ways to dereference a variable
     action: shell echo $HOME $port {{ port }}