• Fix python-requests installations for Ubuntu >= 14.04 LTS. #631, #632, #633
• Install python-crypto from Chris Lea's PPA for Ubuntu < 14.04
• Exit the git checkout directory before deleting it. Thanks Bret Fisher. #634
• Use prefix /usr for centos git install. Thanks Stanislav B. #638
• Drop Ubuntu EOL versions. All Ubuntu version before 12.04.
• Make sure python-dev is installed wheb trying to install tornado from PyPi. #640