allow it to comment at the end of line

A comment at the end of line seems to be allowed in Vim script.
But it's not in `describe`, `it` and other vspec blocks.
I modified a regexp for parsing and make it possible to comment at the end of line.

I implemented this feature because I want to fold a block with `" {{{` like below.

```vim
describe 'hoge()' " {{{

    it 'returns "hoge"' " {{{
    end
    " }}}

end
" }}}
```