Removed deprecated options `:hint_class`, `:group_by`, `:group_label`, `:find_options` and `:value`

Would love some review on this. Probably best to review commit-by-commit rather than a whole diff. Would particularly like review of 1fe253f, especially [this line](https://github.com/justinfrench/formtastic/commit/1fe253ff9747b869dd779f74467f4977c0f26349#L2R87).