Remove company-ess. The functionality has been included into ESS itself

[Lompik]

This package provide completion for company for the ESS package. ESS is now providing built-in support for company (emacs-ess/ESS@03ed3a0) on March 1st . Users should upgrade to the latest ESS.

[purcell]

Oh. That's a shaky implementation on the ESS side, to be honest. ESS doesn't declare a package dependency on company, even though it unconditionally defaults to using company for completion, and ess-r-completion.el won't byte-compile cleanly without it installed. Very odd to have a file which provides both auto-complete and company completion backends, since the two systems are generally mutually exclusive.