Merge remote-tracking branch 'xnat-web-custom-pages/master' into HEAD

src/main/webapp/WEB-INF/tags/page/head.tag

src/main/webapp/WEB-INF/tags/page/restricted.tag

src/main/webapp/WEB-INF/tags/page/xnat.tag

src/main/webapp/page/admin/content.jsp

.../webapp/page/admin/data/config/site-admin-sample-new.yaml

src/main/webapp/page/admin/site-config/content.jsp

src/main/webapp/page/admin/site-config/index.jsp

src/main/webapp/page/admin/site-config/siteConfig.js

src/main/webapp/page/admin/spawner/content.jsp

src/main/webapp/scripts/xnat/ui/panel.js

src/main/webapp/scripts/xnat/ui/templates.js