Made RecentlyUsedContainer.keys() thread-safe on Python 3, removed unnecessary copy on Python 2
Merge pull request #485 from abacabadabacaba/master

Small fixes to RecentlyUsedContainer (improved thread-safety in Py3).
Disable SSL v2 and v3

These SSL protocols are flawed. See
http://en.wikipedia.org/wiki/Transport_Layer_Security#Security for more
information.