recaptcha not showing on admin login

[pylorak]

Correctly configured recaptcha only shows up on user login, but not on admin login page.

This way it leaves the admin login completely unprotected.

It is dangerous to fix this though until #891 is fixed, because if #891 is not fixed, making the captcha appear on admin login would lock out the admin user from the whole installation.

[My1]

while we are at it, the setting of a captcha should involve solving exactly said captcha, as a config test.

but I think there should be options, because recaptcha is an external service after all, meaning if it fails, well it hurts so there should also be an option to have captcha only for the users and instead for example apply limits to the admin logon.

[ervee]

If you can enable/disable captcha on admin login via application.ini that would be fine by me. If the external service fails, just disable en be fina again.