Explicitly use SSLv3 for post-receive hook

I had the problem that mirrors where not automatically updated. After a lot of debugging of the post-receive hook I found the reason to be the following:

When Redmine runs on mod_passenger with apache2 with SSL on Debian 7 the post-receive hook fails. Apache2's mod_ssl configuration disables SSLv2 for security reasons. Ruby 1.9.3 still tries to connect using SSLv2 and fails to establish the connection. This PR changes the ssl version to SSLv3.
Merge pull request #53 from hameno/patch-1

Explicitly use SSLv3 for post-receive hook