Deprecate one time ticket (2) (#156)

Created by: ikedas

This may fix (partially) #156 .

• family_signoff action no longer does use one-time ticket.

(This PR depends on PR #853 .)

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Change

URL for this action became

wwsympa_url_/family_signoff/_family_?email=_email@add.ress

that was previously

wwsympa_url_/family_signoff/_family_/_email@add.ress

This change is required to handle e-mail addresses containing solidus (/) properly.