Fix NPE in setup wizzard by calling loadOpenfireProperties()

javax.servlet.ServletException: java.lang.ExceptionInInitializerError
	at org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:858)
	at org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:791)
	at org.jivesoftware.openfire.admin.setup.setup_002dfinished_jsp._jspService(setup_002dfinished_jsp.java:191)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
	at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:738)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1651)
	at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:118)
	at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:52)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1639)
	at org.jivesoftware.util.LocaleFilter.doFilter(LocaleFilter.java:74)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1639)
	at org.jivesoftware.util.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:50)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1639)
	at org.jivesoftware.admin.PluginFilter.doFilter(PluginFilter.java:78)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1639)
	at org.jivesoftware.admin.AuthCheckFilter.doFilter(AuthCheckFilter.java:164)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1631)
	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:549)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
	at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:568)
	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:221)
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1111)
	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:478)
	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:183)
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1045)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
	at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:199)
	at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:109)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97)
	at org.eclipse.jetty.server.Server.handle(Server.java:462)
	at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:279)
	at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:232)
	at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:534)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:607)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:536)
	at java.lang.Thread.run(Thread.java:744)
Caused by: java.lang.ExceptionInInitializerError
	at org.jivesoftware.openfire.admin.AdminManager.getInstance(AdminManager.java:74)
	at org.jivesoftware.openfire.admin.setup.setup_002dfinished_jsp._jspService(setup_002dfinished_jsp.java:145)
	... 34 more
Caused by: java.lang.NullPointerException
	at org.jivesoftware.util.JiveGlobals.migrateProperty(JiveGlobals.java:782)
	at org.jivesoftware.openfire.admin.AdminManager.initProvider(AdminManager.java:117)
	at org.jivesoftware.openfire.admin.AdminManager.<init>(AdminManager.java:86)
	at org.jivesoftware.openfire.admin.AdminManager.<init>(AdminManager.java:47)
	at org.jivesoftware.openfire.admin.AdminManager$AdminManagerContainer.<clinit>(AdminManager.java:53)
	... 36 more