Add explicit tailing of logs

@bfulton @nahiluhmot 

This pull requests enables SSH forking once a connection to an instance has been made that will tail the syslog (or whatever log files you request) until all of the instances are healthy.

The tests written cannot be run on CI since it requires an SSH connection.  At this point I am not sure if we can configure the SSH server for travis to allow itself to login to itself, so it can only be run locally.
You might be able to set an [`at_exit`](http://www.ruby-doc.org/core-2.1.5/Kernel.html#method-i-at_exit) handler here which closes the connection.