rose suite-hook --mail: configurable email host

Email host defaults to `localhost` if not configured.
Merge pull request #947 from matthewrmshin/rose-suite-hook.mail.host

rose suite-hook --mail: configurable email host
Clarify "timeout".
Merge pull request #954 from arjclark/rose-doc-explain-timeout

Clarify "timeout".
Merge branch 'master' into inherit