[imp] reCaptcha implementation for IMP.

[Chuck Hagenbuch]

Quoting Tobias Drewry <tdrewry at bu.edu>:

> I have just completed adding reCaptcha support to our installs of  
> IMP 4.3.4 and, our well aged, IMP 4.0.4.
>
> If there is any interest in a patch, I'd be happy to put one together.

What pages/forms did you put the captchas on?

-chuck