test(context): Change the StringSliceFlag to a pointer

StringSliceFlag needs to be a pointer, and not a struct. Also formatted the test.

See: https://github.com/urfave/cli/pull/1126 for a description of the regression
tested for.

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

context_test.go

@@ -535,11 +535,11 @@ func TestCheckRequiredFlags(t *testing.T) {
 			parseInput: []string{"-n", "asd", "-n", "qwe"},
 		},
 		{
-			testCase: "required_flag_with_short_alias_not_printed_on_error",
-			expectedAnError: true,
+			testCase:              "required_flag_with_short_alias_not_printed_on_error",
+			expectedAnError:       true,
 			expectedErrorContents: []string{"Required flag \"names\" not set"},
 			flags: []Flag{
-				StringSliceFlag{Name: "names, n", Required: true},
+				&StringSliceFlag{Name: "names, n", Required: true},
 			},
 		},
 	}