Resolve linter errors exposed by fixed Makefile

- TravisCI didn't like "POSIX" ::= syntax

pkg/storage/lock.go

@@ -5,8 +5,12 @@ import (
 	"sync"
 )
 
+// HashLock holds a fixed length array of mutexes.  This approach allows concurrent mailbox
+// access in most cases without requiring an infinite number of mutexes.
 type HashLock [4096]sync.RWMutex
 
+// Get returns a RWMutex based on the first 12 bits of the mailbox hash.  Hash must be a hexidecimal
+// string of three or more characters.
 func (h *HashLock) Get(hash string) *sync.RWMutex {
 	if len(hash) < 3 {
 		return nil