Faster report view with eager loading

http://projects.puppetlabs.com/issues/8047

Before:
```
  ResourceStatus Load (0.3ms)  SELECT "resource_statuses".* FROM "resource_statuses" WHERE "resource_statuses"."report_id" = 28 ORDER BY resource_type, title
   (0.2ms)  SELECT COUNT(*) FROM "resource_events" WHERE "resource_events"."resource_status_id" = 83
  ResourceEvent Load (0.2ms)  SELECT "resource_events".* FROM "resource_events" WHERE "resource_events"."resource_status_id" = 83
   (0.2ms)  SELECT COUNT(*) FROM "resource_events" WHERE "resource_events"."resource_status_id" = 82
  ResourceEvent Load (0.2ms)  SELECT "resource_events".* FROM "resource_events" WHERE "resource_events"."resource_status_id" = 82
   (0.2ms)  SELECT COUNT(*) FROM "resource_events" WHERE "resource_events"."resource_status_id" = 84
  ResourceEvent Load (0.3ms)  SELECT "resource_events".* FROM "resource_events" WHERE "resource_events"."resource_status_id" = 84
  Rendered reports/_resource_statuses.html.haml (11.4ms)
```

After:
```
  ResourceStatus Load (0.1ms)  SELECT "resource_statuses".* FROM "resource_statuses" WHERE "resource_statuses"."report_id" = 28 ORDER BY resource_type, title
  ResourceEvent Load (0.2ms)  SELECT "resource_events".* FROM "resource_events" WHERE "resource_events"."resource_status_id" IN (83, 82, 84)
  ResourceStatus Load (0.2ms)  SELECT "resource_statuses".* FROM "resource_statuses" WHERE "resource_statuses"."report_id" = 28
  Rendered reports/_resource_statuses.html.haml (4.5ms)
```