Make captcha stateless

This is a small MR that passes the encrypted data backend sends back to it to check the answer. Connected with this BE MR: pleroma!585 (merged)

mentioned in merge request pleroma!585 (merged)

added 1 commit

• 9d4f472f - Add a translation to the "get a new captcha" string

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added 1 commit

• 10642df5 - Add a translation to the captcha strings in the registration form

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resolved all discussions

merged

mentioned in commit e59b67e1