Make SCP fit naming conventions when copying directory recursively

* Factored file manipulation steps to a steps file.
* Added missing features for copy of directories over SCP.
* Refactored SCP operations.
* Make SCP prepare a temporary dir to copy to, then move the actual
artifact to the expected location/name.
* Fixed specs.
Merge branch 'master' of github.com:servebox/electric_sheep

Conflicts:
	spec/electric_sheep/transports/scp_spec.rb