Fix path for nsis ant task

Change-Id: I37c23e0194e325224fb2dc1678f79bb7d44a5eb6
Reviewed-on: http://gerrit.dmdirc.com/2393
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Automatic-Compile: DMDirc Build Manager

build-installer.xml

@@ -4,7 +4,9 @@
 
     <target name="-init-installer">
         <taskdef name="nsis" classname="com.danielreese.nsisant.Task">
-            <classpath location="lib/nsisant-1.3.jar" />
+            <classpath>
+                <fileset dir="lib" includes="*nsis*.jar"/>
+            </classpath>
         </taskdef>
 
         <taskdef name="git-describe" classname="org.mdonoughe.JGitDescribeTask">