Add golang configuration samples

Add suggested Go configuration for Vim into the `ftplugin` folder and
the vim-go plugin. We may use this as a template for adding further
language-specific settings in the future for languages that aren't
universally used by the team.

* `fatih/vim-go`: The de-facto Golang Vim plugin.
* `softtabstop=2`: As a side effect of setting how "large" a tab is in
  insert mode, Vim is able to delete tabs with the backspace key in
  Insert mode.
* `compiler go`: Necessary for plugins using the `make` command, such as
  vim-dispatch.
* `listchars=tab:\ \ `: Don't highlight tabs as "»·" as if they were
  problem characters in go files. Also recommended for *sh files and any
  others which which should also be using tabs.
* `go_fmt_command = "goimports"`: Tell vim-go to use the `goimports`
  command rather than `gofmt`, which attempts to find dependencies and
  adds them to your import statement.

vim/ftplugin/go.vim

@@ -0,0 +1,6 @@
+let g:go_fmt_command = "goimports"
+
+setlocal softtabstop=2
+setlocal listchars=tab:\ \ ,trail:·,nbsp:·
+
+compiler go

vimrc.bundles

@@ -28,8 +28,9 @@ call plug#begin('~/.vim/bundle')
 
 " Define bundles via Github repos
 Plug 'christoomey/vim-run-interactive'
-Plug 'kchmck/vim-coffee-script'
 Plug 'ctrlpvim/ctrlp.vim'
+Plug 'fatih/vim-go'
+Plug 'kchmck/vim-coffee-script'
 Plug 'pbrisbin/vim-mkdir'
 Plug 'scrooloose/syntastic'
 Plug 'slim-template/vim-slim'