Adds REST API for issue relations (#7366).

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@6176 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/views/issue_relations/show.api.rsb

@@ -0,0 +1,7 @@
+api.relation do
+  api.id @relation.id
+  api.issue_id @relation.issue_from_id
+  api.issue_to_id @relation.issue_to_id
+  api.relation_type @relation.relation_type_for(@issue)
+  api.delay @relation.delay
+end