Fix g:phpfmt_options problem and fit for phpcbf version 3

[zurazurataicho]

I found two problems about using g:phpfmt_options and phpcbf version 3. Sorry for my pull request include each two issues.

1. Fix g:phpfmt_options
   When I set g:phpfmt_options on my .vimrc, it seemed doesn't work. So I modified treating g:phpfmt_options and g:phpfmt_standard on plugin/phpfmt.vim. My settings for vim-phpfmt is below:

let g:phpfmt_standard = 'PSR2'
let g:phpfmt_options = '--sniffs=Generic.WhiteSpace.ScopeIndent'

2. Fit for phpcbf version 3
   I'm using phpcbf version 3.1.1. When I wrote a PHP code and do :PhpFmt, it doesn't work. Phpcbf version 3 assumes to be a file extension in a filename. If it is not an extension, phpcbf skips process. I added an extension end of a temporary filename.