Option to set default helper application for FTP/SFTP in Cyberduck

[cyberduck]

@dkocher created the issue

Use the LaunchServices Framework to query and register the default handler for URL schemes.

Files and URLs pointing to FTP/SFTP locations in third party applications will then make Cyberduck launch.

This will make the use of applications like MoreInternet and others obsolete.

[cyberduck]

@dkocher commented

As of 34efd71.

[cyberduck]

@dkocher commented

Configurability in Preferences added in e44fbfc.