rest: use `app.delete` instead of `app.del`

`app.del` was deprecated in express.
Merge pull request #82 from strongloop/fix-app-del-warning

[1.x] rest: use `app.delete` instead of `app.del`
1.5.2
Upgrade qs dep
Fix failing test
Add `errors` and `notes` to method metadata

This is a backport of #113 from the master (2.x).
Merge pull request #115 from strongloop/feature/backport-error-and-notes

Add `errors` and `notes` to method metadata
1.6.0