update syntastic, vim-endwise, YouCompleteMe, unite
update easytags config

- add async option to easytags config
- set up javascript tag generation using jsctags
- turn off auto generation of tags on cursor hold
- turn off auto highlighting of tags after generation
update unite config to latest specs
update syntastic, vim-rails
remove unused syntastic syntax checkers
update a handful of plugins

- unite, syntastic, vim-easytags, vim-easytagsmisc,
  vim-pathogen, YouCompleteMe, vim-markdown, vim-surround,
  vimproc, vim-html5, vim-rails