Switch to gometalinter

Only small amount of required checks is enabled,
plan is to enable more linters as issues are fixed in the code.

swift/public_test.go

@@ -2,13 +2,14 @@ package swift
 
 import (
 	"fmt"
-	. "gopkg.in/check.v1"
 	"io/ioutil"
 	"math/rand"
 	"os"
 	"path/filepath"
 	"time"
 
+	. "gopkg.in/check.v1"
+
 	"github.com/ncw/swift/swifttest"
 
 	"github.com/smira/aptly/files"