WIP: Translates optional params

Fixes translation of optional params (params ending with a question mark)

Before:

translate('example/:one/:two?', 'foo')        // => '/example/foo/:two?'
translate('example/:one/:two?', 'foo', 'bar') // => '/example/foo/bar?'

After:

translate('example/:one/:two?', 'foo')        // => '/example/foo/:two?'
translate('example/:one/:two?', 'foo', 'bar') // => '/example/foo/bar'