Don't set autoindent

It's only very rarely that I want this off, but since file type plugins
tend to turn it on when it's desirable, the argument for forcing it
globally is pretty weak.

plugin/sensible.vim

@@ -17,7 +17,6 @@ endif
 
 " Use :help 'option' to see the documentation for the given option.
 
-set autoindent
 set backspace=indent,eol,start
 set complete-=i
 set smarttab