The gitlab-satellites permissions should be 0750

Otherwise the built-in GitLab environment check gives a warning and says to fix it; these are the fixed permissions.

The [installation documentation](https://github.com/gitlabhq/gitlabhq/blob/master/doc/install/installation.md#configure-it) says `sudo chmod u+rwx,g+rx,o-rwx /home/git/gitlab-satellites` which translates to 0750 permissions.