Merge branch 'gh-pages' of https://github.com/spring-projects/gh-pages into gh-pages

.gitignore

@@ -3,7 +3,7 @@
 *~
 _site
 .idea
-*.sw?
+*.sw[op]
 .project
 sample-pages
 .classpath

_includes/billboard.html

@@ -17,10 +17,12 @@
                             <a href="{{ site.github_repo_url }}" class="project-link">
                                 <i class="icon-github"></i>
                             </a>
+{% if site.forum %}
                             <a href="{{ site.forum }}" class="project-link project-link-forum">
                                 <div class="spring-icon spring-icon-forum">
                                 </div>
                             </a>
+{% endif %}
                         </div>
                     </div>