Fix 0012312: NuSOAP web description XSS vulnerability

Bogdan Calin from Acunetix discovered a number of XSS vulnerabilities in
NuSOAP 0.9.5 (bundled with MantisBT) relating to improperly escaped
URLs.

A sample exploit URL is:
/api/soap/mantisconnect.php?1<ScRiPt>prompt(923395)</ScRiPt>

The upstream report for these XSS flaws in NuSOAP is located at the
following URL:
http://sourceforge.net/projects/nusoap/forums/forum/193579/topic/3834005

This patch provides an interim fix for MantisBT users until upstream
makes a new release.