overhaul of vim setup

vim-files/vim/ftplugin/elixir.vim

@@ -1,10 +0,0 @@
-let g:neomake_elixir_mix_maker = {
-      \ 'exe' : 'mix',
-      \ 'args': ['compile', '--warnings-as-errors'],
-      \ 'cwd': getcwd(),
-      \ 'errorformat':
-        \ '** %s %f:%l: %m,' .
-        \ '%f:%l: warning: %m'
-      \ }
-
-let g:neomake_elixir_enabled_makers = ['mix']