Checkbox for crediting the translator (Translator)

Adding a checkbox before submitting the changes would make it easier for project owners to see if their name is okey for crediting (easier for project owner to see if it's okey to give credit publicly instead of having to e-mail each separate translator)

Quote from `localize.im/pages/settings` with the '_Email address_' description
"This allows the project owners to contact you, e.g. to check back on certain issues or to **ask if they may give public credit to you**."

**Example:**