Honour global serverip setting.

The idea behind serverip set in [global] is to set the address that
oscam binds to by default but the setting was not used properly.

For modules it only worked if reader->l_port was set but for webif
it wasn't working at all.

This fixes ticket #3206.

git-svn-id: http://streamboard.de.vu/svn/oscam/trunk@8515 4b0bc96b-bc66-0410-9d44-ebda105a78c1