switch shell to silence tty error

workaround from the great research at:

https://github.com/mitchellh/vagrant/issues/1673#issuecomment-28287711

<3 to @bradfeehan for his research
switch to static ssh-config caching

should be faster and more stable

also fixes issue with 50211c20c2fd2b144dcd58d06e0fdb6448532829 where the
ssh port was not correct
cut v0.5.1