Support setting most SSH options
Check that SSH host and command are given
Rename openssh.SSHCommand to openssh.Command
Optionally change SSH user and port with -H

-H now accepts the format [user@]hostname[:port]
Fix typo
Allow to log formatted strings
Log package preamble
Make use of new log functions
Log start and end of execution
Allow to configure ssh via config file
Replace `vagrant ssh` with ssh proper

Based on the output of `vagrant ssh-config`.
Support rsync over ssh