Allow hacking 0.6.0 and fix versions

* versions of pep8, pyflakes and hacking are fixed;
* hacking updated to 0.6.0, errors fixed.

Change-Id: I11eeb234e3079efb3be3162ac8d82196a1bfc722
diff --git a/test-requirements.txt b/test-requirements.txt
index 8b2c2da..974f05f 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1 +1 @@
-hacking>=0.5.3,<0.6
+hacking>=0.5.6,<0.7