Support localizable File for IASKAppSettingsWebViewController

[funnel20]

Resolves issue #510

[futuretap]

Good idea to support localization for the File parameter. However, we should use IASK's own localization scheme (localizedObjectForKey: instead of NSLocalizedString(). Then the localized URLs are in the same localized string files than the rest of the settings keys.

[funnel20]

You're absolutely right, I jumped too fast to conclusions.
Then I need your help a bit, I don't know the exact coding style that you prefer. Or you can make the improvement yourself.

[futuretap]

Replacing NSLocalizedString(specifier.file, nil) with [specifier localizedObjectForKey:kIASKFile] should do it.

[funnel20]

Replacing NSLocalizedString(specifier.file, nil) with [specifier localizedObjectForKey:kIASKFile] should do it.

Done and verified