Add AddArguments to TableEntry

[kaovilai]

For usecase like below to reduce repeating arguments in each entry increasing test description complexity unnecessarily.

var declaration is unnecessary but here for object type visibility.

for i, _ := range awsTests {
		var entry *TableEntry
		entry = &awsTests[i]
		entry.AddArguments(Label("aws"))
	}
	genericTests = append(genericTests, awsTests...)
}