Remove cucumber monkey patch translating steps:

It was initially added to allow reuse of aruba cucumber steps, using
`must' instead of `should'. This is creating more harm than good, hence
we remove it and implements all missing steps, using aruba API.

features/steps/ssh_steps.rb

@@ -1,6 +1,6 @@
 # FIXME: current home directory shouldn't be changed here, maybe we should use
 # a tag for features needing a fake home directory.
-Given(/^an SSH config with:$/) do |config|
-  ENV['HOME'] = File.expand_path current_dir
+Given /^an SSH config with:$/ do |config|
+  ENV['HOME'] = File.expand_path(current_dir)
   write_file '.ssh/config', config
 end