Merge tag 'v1.4.2'

1.4.2
docs: document remote method `description`
Merge pull request #127 from strongloop/feature/fix-remoting-doc

docs: document remote method `description`
Add missing assert in user model
Add an empty transportsIndex to the mail connector by default
Merge pull request #129 from strongloop/fix/missing-assert

Add missing assert in user model
Provide sane default for email connector transports
Implement `app.listen`

The method starts a http server on the host & port configured
in the app config.
Merge pull request #124 from strongloop/feature/app-listen

Implement `app.listen`
Describe loopback.ValidationError in API docs.
Merge pull request #121 from strongloop/feature/validation-error-apidocs

Describe `loopback.ValidationError` in API docs.
Merge pull request #130 from strongloop/fix/mail-transports

Fix/mail transports
Fix incorrect transports
Merge pull request #136 from strongloop/fix/mail-transports

Fix incorrect transports
1.4.3