Support NeoVim

[TamaMcGlinn]

This plugin uses Vim 8 jobs / channels, which are not supported in NeoVim because it has a jobs API which is supposedly better. In any case, it is perfectly possible to support both NeoVim and Vim, if we use the jobs API when has('nvim').

[ldrumm]

I don't use neovim and don't really have the time to add support for a platform I don't use right now. However, patches are always welcome and I'll be able to review and merge it if you want to make these changes.