All the necessary things for setup.py to build cffi stuff
six is now required at build time
Some flake8 fixes
Merge branch 'master' into setup-install-extension

Conflicts:
	setup.py
Explanatory comment
Merge branch 'master' into setup-install-extension

Conflicts:
	cryptography/hazmat/bindings/openssl/binding.py
Re-add the ext_package decleration to the moved verify() call
Check to see if a binding is available before trying to install it
flake8
Merge branch 'master' into setup-install-extension
This is dangerous
Merge pull request #392 from alex/setup-install-extension

All the necessary things for setup.py to build cffi stuff