fix(requirements): pull in the the fix branch of cryptography until official release happens

OpenSSL 1.0.2g introduces some CVE fixes but also broke basic APIs and that broke pypi cryptography. We can not pin to a lower openssl on Alpine either

Author: helgi

rootfs/requirements.txt

@@ -15,3 +15,4 @@ pytz==2015.7
 PyYAML==3.11
 requests==2.9.1
 simpleflock==0.0.3
+git+https://github.com/pyca/cryptography.git@1.2.x#egg=cryptography