add six to requrements (fixes allure-framework#67 via allure-framework#68)

Author: sseliverstov

allure-pytest/setup.py

@@ -27,6 +27,7 @@
 
 install_requires = [
     "pytest>=2.7.3",
+    "six>=1.9.0",
     "allure-python-commons==2.0.0b2"
 ]
 

allure-python-commons/setup.py

@@ -14,6 +14,7 @@
 
 install_requires = [
     "attrs>=16.0.0",
+    "six>=1.9.0"
 ]
 
 if sys.version_info < (3, 4):

allure-python-testing/setup.py

@@ -4,7 +4,8 @@
 VERSION = "2.0.0b2"
 
 install_requires = [
-    "pyhamcrest>=1.9.0"
+    "pyhamcrest>=1.9.0",
+    "six>=1.9.0"
 ]