Can't pass array into flashOnly and flashExcept

If you pass an array into `flashOnly` or `flashExcept` like in other methods by the time it gets to `only` or `except` we have `[0 => ['email', 'name']]` etc. 
Merge pull request #285 from Robbo-/patch-2

Can't pass array into flashOnly and flashExcept of the Request class