ACCEPTED_STUDENT_VISIBILITY added.

Documents, whose dashboard visibility contains this tag, will be shown only to students who have at least one project.
diff --git a/app/soc/logic/document.py b/app/soc/logic/document.py
index 7d11dc0..42932ae 100644
--- a/app/soc/logic/document.py
+++ b/app/soc/logic/document.py
@@ -35,6 +35,9 @@
   visibilities = []
   if data.is_student:
     visibilities.append(document_model.STUDENT_VISIBILITY.identifier)
+    if data.student_info.number_of_projects > 0:
+      visibilities.append(
+          document_model.ACCEPTED_STUDENT_VISIBILITY.identifier)
   if data.is_org_admin:
     visibilities.append(document_model.ORG_ADMIN_VISIBILITY.identifier)
   if data.is_mentor:
diff --git a/app/soc/models/document.py b/app/soc/models/document.py
index 5755f32..d168678 100644
--- a/app/soc/models/document.py
+++ b/app/soc/models/document.py
@@ -55,6 +55,10 @@
 MENTOR_VISIBILITY = DashboardVisibility('mentor', 'Mentors')
 ORG_ADMIN_VISIBILITY = DashboardVisibility(
     'org_admin', 'Organization Admins')
+# TODO(daniel): the last one should be moved somewhere to a SoC specific
+# module, as it makes sense only for those programs
+ACCEPTED_STUDENT_VISIBILITY = DashboardVisibility(
+    'accepted_student', 'Accepted Students')
 
 
 class Document(soc.models.work.Work):
@@ -73,6 +77,7 @@
   # list of all possible dashboard visibilities
   DASHBOARD_VISIBILITIES = [
       STUDENT_VISIBILITY, MENTOR_VISIBILITY, ORG_ADMIN_VISIBILITY,
+      ACCEPTED_STUDENT_VISIBILITY,
       ]
 
   DOCUMENT_ACCESS = ['admin', 'restricted', 'member', 'user']