Add localized strings in Traditional Chinese

P.S. is there a missing placeholder in the string [@"Password reset email sent to"](https://github.com/bcylin/uservoice-ios-sdk/blob/master/Resources/en.lproj/UserVoice.strings#L115) ? (at [UVSigninManager.m#L132](https://github.com/bcylin/uservoice-ios-sdk/blob/master/Classes/UVSigninManager.m#L132))

```objc
[NSString stringWithFormat:NSLocalizedStringFromTable(@"Password reset email sent to", @"UserVoice", nil), email];
```