RAA dead link cleanup

[Daniel Berger]

Hi all,

The RAA admin did a massive link check and found 506 dead links.
Please check the list and see if one of your projects is on the list.

To the RAA admin: some of these projects appear to have been merged
into the standard library and should probably be deleted (unless they
are unrelated to the version merged into stdlib):

- forwardable
- ruby-sha1
- scanf_for_ruby
- shell
- testunit
- syslog

Regards,

Dan