[horde] upgrade imp to 4.2

[Chuck Hagenbuch]

Quoting Joe Fisher <Joe.Fisher at citylightsmedia.com>:

>> Notice: Undefined index: cachejs in
>> /usr/local/cpanel/base/horde/imp/lib/IMP.php on line 1872
>
> I was wondering if someone can point out what I've missed in my attempt
> to update to 4.2 from 4.1?

Regenerating your configuration files. From horde/docs/UPGRADING:

After updating to a newer Horde version, or a newer version of **any** Horde
application, you **always** need to update **all** configuration files.

-chuck