Fix windows-slaves-plugin

2669e4a8 extracted windows-slaves code
to a separate plugin.
However in the process, it introduced a dependency conflict.
core -> j-interop -> jcifs (1.2.19)
whereas
windows-slaves-plugin -> ... -> jcifs (1.3.17-kohsuke-1)

This was causing NoSuchMethodError while launching windows slaves

pom.xml

@@ -215,6 +215,11 @@ THE SOFTWARE.
         <artifactId>commons-logging</artifactId>
         <version>1.1.3</version>
       </dependency>
+      <dependency>
+        <groupId>org.samba.jcifs</groupId>
+        <artifactId>jcifs</artifactId>
+        <version>1.3.17-kohsuke-1</version>
+      </dependency>
     </dependencies>
   </dependencyManagement>
   <dependencies>