Include tenants from other regions in RBAC

accessible_tenant_ids are tenant ids determined
for selection of resources by certain tenant strategy.

This update extend tenant ids about tenant ids from
other regions. This tenant ids are determined by
finding tenant with same name as we have in other
regions and tenant is used to get tenant ids
by certaion tenant strategy.

app/models/tenant.rb

@@ -90,8 +90,16 @@ def all_subprojects
     self.class.descendants_of(self).where(:divisible => false)
   end
 
+  def regional_tenants
+    self.class.regional_tenants(self)
+  end
+
+  def self.regional_tenants(tenant)
+    where(arel_table.grouping(arel_attribute(:name).eq(tenant.name)))
+  end
+
   def accessible_tenant_ids(strategy = nil)
-    (strategy ? send(strategy) : []).append(id)
+    (strategy ? regional_tenants.map(&strategy.to_sym).flatten : []) + regional_tenants.ids
   end
 
   def name