update constants from 3.3
regen constants
update test_security with 3.3 constant changes
try to install pypy from ppa

ref: alex/cryptography/pull/62
skip CURVE_ sock opts in test_int_sockopts

they are only available when linked with libsodium
cleanup sockets in test_security

pypy can't be trusted to garbage collect
test identity roundtrip (pypy is failing right now)
fix bytes sockopts in CFFI backend
no longer expect anything to fail on travis
Merge pull request #416 from minrk/33consts

update 3.3 constants

and enable travis builds with pypy and libzmq-master

fix some CFFI backend bugs found along the way.