Replacing bash ssh calls to the Net::SSH library.  

I tested this and it works.  This replaces all the `ssh ....` with net::ssh library.  I've run the whole test suite against this branch and everything passes.  
Something is wrong here: you are checking `output` which now is a hash and not a string.

You either have to do:
```ruby
fail if output[:stdout].include?('ERROR')
```
or
```ruby
fail unless output[:stderr].empty?
```