Add license link to README.
Travis CI: Use current version of Go

Signed-off-by: Ondrej Kupka <ondra.cap@gmail.com>
Merge pull request #85 from tchap/travis-go-1.1.1

Travis CI: Use current version of Go
Implement zmq_disconnect

Signed-off-by: Ondrej Kupka <ondra.cap@gmail.com>
Merge pull request #89 from tchap/socket-disconnect

Implement zmq_disconnect
Generate SetTCPAcceptFilter(string).
Generate SetROUTERMandatory(bool).
Generate SetXPUBVerbose(bool).
Generate MaxMsgSize().
Generate DelayAttachOnConnect().
Generate IPv4Only().
Add SetTCPAcceptFilterNil.