Added ftdetect files for vim to detect shell scripts from shebang line.

vim/vim/ftdetect/bash.vim

@@ -0,0 +1,7 @@
+fun! s:DetectNode()
+    if getline(1) == '#!/usr/bin/env bash'
+        set ft=sh
+    endif
+endfun
+
+autocmd BufNewFile,BufRead * call s:DetectNode()

vim/vim/ftdetect/sh.vim

@@ -0,0 +1,7 @@
+fun! s:DetectNode()
+    if getline(1) == '#!/usr/bin/env sh'
+        set ft=sh
+    endif
+endfun
+
+autocmd BufNewFile,BufRead * call s:DetectNode()

vim/vim/ftdetect/zsh.vim

@@ -0,0 +1,7 @@
+fun! s:DetectNode()
+    if getline(1) == '#!/usr/bin/env zsh'
+        set ft=sh
+    endif
+endfun
+
+autocmd BufNewFile,BufRead * call s:DetectNode()