remove link to zmqweb
remove no-longer-required initthreads extension
Merge pull request #505 from minrk/rmweb

remove link to zmqweb
remove unused rebuffer
Merge pull request #506 from minrk/import-init

remove some obsolete Cython files
handle terminated gc context

closes #507
Merge pull request #509 from minrk/gc-teardown

handle terminated gc context
validate ZAP messages

adds checks that ZAP messages are actually valid

Bugs in zeromq (e.g. zeromq/libzmq#948) can result in invalid messages.
These shouldn't result in exceptions in the auth handler.
pass on serial socket example

works on 3.4
Merge pull request #512 from minrk/libzmq-948

validate ZAP messages
Merge pull request #513 from minrk/serialsocket

pass on serial socket example
add travis status to readme