This simple logic scans for ISO files on the base URL of the mirror.

This requires the "socksify" library which is not in Debian:

http://www.rubydoc.info/gems/socksify/1.6.0/frames

So we are loading this library only when this option is used.

Actually, supporting HTTP proxy is not a good idea because they
tend to cache content and this is problematic in our use case.

There is no Ruby library in Debian Wheezy for SOCKS proxying, see #8054.

Otherwise some HTTP related classes complain.

The --no-verbose option otherwise prevents from analyse the speed of the download.

This way we get rid of the progress bar output but still have an output
of the command.

Conflicts:
	check-mirrors.rb

Strangely it is not inheriting StandardError so it won't be catched by
default.