Revert "remove eiffelstudio due to upstream changes"

This reverts commit a2089acde2d08ccf762f0a26f94f40b71c4baf96.
It seems to be available for download again.
add host and dig commands to devenv
add ftp and tftp clients

These are useful for testing other services.
fix test failure due to upstream rubocop changes

* bbatsov/rubocop@ff167d8f changed Rubocop -> RuboCop
* require min version of rubocop to ensure bundle has the above commit
latest rubocop now prefers backticks over %x

upstream rubocop now recommends to use backticks instead of %x
rspec/mocha now requires symbol for mock_with

Resolves error:

    Unknown mocking framework: "mocha".
    Pass a module or one of [:rspec, :flexmock, :rr, :mocha, :nothing]
run spec_standalone to support old and current rake tasks

Latest bundle seems to not invoke :spec_standalone from :spec,
so invoke it directly. This ensures the harness runs regardless
of which bundle is installed.