use sw=2 for vim files

vimrc

@@ -111,6 +111,7 @@ if has("autocmd")
     autocmd FileType text setlocal textwidth=78
     autocmd BufRead,BufNewFile *.icf set syntax=cpp
     autocmd Syntax ruby setlocal sw=2 ts=2 sts=2 iskeyword+=@-@,?
+    autocmd Syntax vim setlocal sw=2 ts=2 sts=2
     autocmd BufRead,BufNewFile *.di set filetype=d
     autocmd BufNewFile,BufReadPre *.h.erb let b:eruby_subtype = "c"
     autocmd BufNewFile,BufRead *.[ch].erb setlocal sw=4 ts=4 sts=4