Set filetype based on node shebang

Recognizes the node shebang line and sets the filetype to javascript.
Syntax highlights the shebang as well.

ftdetect/javascript.vim

@@ -0,0 +1,6 @@
+function! s:DetectJS()
+    if getline(1) =~# '^#!.*/bin/env\s\+node\>'
+        setfiletype javascript
+    endif
+endfunction
+autocmd BufNewFile,BufRead * call s:DetectJS()

syntax/javascript.vim

@@ -28,6 +28,10 @@ setlocal iskeyword+=$
 
 syntax sync fromstart
 
+"" syntax coloring for Node.js shebang line
+syn match shebang "^#!.*/bin/env\s\+node\>"
+hi link shebang Comment
+
 "" JavaScript comments"{{{
 syn keyword javaScriptCommentTodo      TODO FIXME XXX TBD contained
 syn match   javaScriptLineComment      "\/\/.*" contains=@Spell,javaScriptCommentTodo