remove configurations for neocomplcache
reset configurations for neocomplcache

ref. https://github.com/Shougo/neocomplcache.vim/blob/546508d52e57fda5c3bf2fa517a0bbc320a7f31b/README.md
add a neocomplcache configuration for using it with tpope/vim-rails

avoid the following error;
  ^@  completefunc=syntaxcomplete#Complete^@^ILast set from ~/.vim/bundle/neocomplcache/autoload/neocomplcache/init.vim
  Another plugin set completefunc! Disabled neocomplcache.