Run golint and go vet (#276)

Cleanup the errors and removed deadcode along the way. The leaves
some error laying around, mostly about commenting exported identifier.
We should look hard if those really are needed.

middleware/file/secondary.go

@@ -176,7 +176,6 @@ Restart:
 			}
 		}
 	}
-	return nil
 }
 
 // The maximum difference between two serial numbers. If the difference between