Fix all linting errors

Disabled gocylco for now, need to use gometalinter to disable
conditionally. There are also a lot more linters we could use, but they
cause too many issues to start today.

internal/sctp/error_cause.go

@@ -56,7 +56,6 @@ const (
 	protocolViolation                      errorCauseCode = 13
 )
 
-// nolint: gocyclo
 func (e errorCauseCode) String() string {
 	switch e {
 	case invalidStreamIdentifier: