[emacs mode] rm tern-ido-complete.el

Hi Marijn,

Sorry to bother you with this stuff, but I'd like to remove `tern-ido-complete.el`, because I generalized the solution for any kind of `completion-in-region` and created a separate package, called [ido-at-point](https://github.com/katspaugh/ido-at-point). Of course, it works pretty well with Tern, too.

I'll send a patch to remove `tern-ido-complete.el` from the MELPA recipe as well (if you accept this one).