test(context): Change the StringSliceFlag to a pointer

StringSliceFlag needs to be a pointer, and not a struct.

See: urfave#1126 for a description of the regression
tested for.

Signed-off-by: Ole Petter <ole.orhagen@northern.tech>

context_test.go

@@ -539,7 +539,7 @@ func TestCheckRequiredFlags(t *testing.T) {
 			expectedAnError: true,
 			expectedErrorContents: []string{"Required flag \"names\" not set"},
 			flags: []Flag{
-				StringSliceFlag{Name: "names, n", Required: true},
+				&StringSliceFlag{Name: "names, n", Required: true},
 			},
 		},
 	}