added intervention controller and stuff

app/policies/intervention_policy.rb

@@ -0,0 +1,34 @@
+class InterventionPolicy < AdminOrAuthorPolicy
+  def author?
+    @user == @record.author
+  end
+  private :author?
+
+  def batch_update?
+    admin?
+  end
+
+  def show?
+    @user.internal_user?
+  end
+
+  [:clone?, :destroy?, :edit?, :update?].each do |action|
+    define_method(action) { admin? || author?}
+  end
+
+  [:reload?].each do |action|
+    define_method(action) { everyone }
+  end
+
+  class Scope < Scope
+    def resolve
+      if @user.admin?
+        @scope.all
+      elsif @user.internal_user?
+        @scope.where('user_id = ? OR public = TRUE', @user.id)
+      else
+        @scope.none
+      end
+    end
+  end
+end