Merge pull request scala#407 from sjrd/ask-to-specify-preferred-project

Ask students to specify their preferred project.

Author: densh

gsoc/2016.md

@@ -263,4 +263,10 @@ feel free to include anything that you think is relevant:
     *   Do you plan to have any other commitments during SoC that may
         affect you work? Any vacations/holidays planned? Please be
         specific as much as you can.
+*   If you apply to more than one GSoC project, especially if you also apply
+    for a project in another organization, specify which project has your
+    preference. In case two organizations choose to accept your applications,
+    we can then give you the project that is most important to you.
+    Preferring the project of another organization will *not* influence our
+    decision whether to accept your application.
 *   Contact details (**very important!**)