fix missing shell repo variable in setup

[flowerett]

After merging #263 I realize that $repo variable is not present anymore and mina setup fail.

Here is a fix.

In addition:

• all sed's magick replaced by Ruby regexps
• a small check for ssh-key existence have been added

It's also possible to fix previous bash version like that:

if repository
    queue %[
      repo="#{repository}" &&
      repo_host=`echo $repo | sed -e 's/.*@//g' -e 's/:.*//g'` &&
      repo_port=`echo $repo | grep -o ':[0-9]*' | sed -e 's/://g'` &&
      if [ -z "${repo_port}" ]; then repo_port=22; fi &&
      if ! ssh-keygen -H  -F $repo_host &>/dev/null; then
        ssh-keyscan -t rsa -p $repo_port -H $repo_host >> ~/.ssh/known_hosts
      fi
    ]
end

but personally I prefer Ruby :)

Regexp have been tested against following repo strings:

[email protected]:1111:tmp/repo.git
git://host1.xz/~user/path/to/repo.git/
ssh://[email protected]:2222/path/to/repo.git/
ssh://host3.xz:3333/path/to/repo.git/
[email protected]:/path/to/repo.git/
https://host5.xz/path/to/repo.git/