Add sinatra ftdetect based on Sinatra::Base

Author: halorgium

ftdetect/sinatra.vim

@@ -0,0 +1,9 @@
+autocmd BufNewFile,BufRead * call s:CheckForSinatraApp()
+
+function! s:CheckForSinatraApp()
+  if &filetype !~ '\(^sinatra$\|\.sinatra$\|^sinatra\.\|\.sinatra\.\)'
+    if search(' < Sinatra::Base', 'nwc')
+      set filetype+=.sinatra
+    endif
+  endif
+endfunction