Disable compileall test for contrib/ in tox -e py34

(This is supposed to be temporary, until the code under contrib/ gets
cleaned up from all the remaining print statements.)

tox.ini

@@ -26,7 +26,7 @@ whitelist_externals = make
 [testenv:py34]
 commands =
     python --version
-    python -m compileall -fq -x 'lib/ansible/module_utils|lib/ansible/modules' lib test contrib
+    python -m compileall -fq -x 'lib/ansible/module_utils|lib/ansible/modules' lib test
     make tests
 deps = -r{toxinidir}/test-requirements.txt
 whitelist_externals = make