cleanup: rename package and vendor dependencies for old go versions

Fixes #8 and begins to address deployability.

vendor/github.com/pebbe/zmq4/doc.go

@@ -0,0 +1,20 @@
+/*
+A Go interface to ZeroMQ (zmq, 0mq) version 4.
+
+For ZeroMQ version 3, see: http://github.com/pebbe/zmq3
+
+For ZeroMQ version 2, see: http://github.com/pebbe/zmq2
+
+http://www.zeromq.org/
+
+See also the wiki: https://github.com/pebbe/zmq4/wiki
+
+A note on the use of a context:
+
+This package provides a default context. This is what will be used by
+the functions without a context receiver, that create a socket or
+manipulate the context. Package developers that import this package
+should probably not use the default context with its associated
+functions, but create their own context(s). See: type Context.
+*/
+package zmq4