create a new document for Customizing Metabase which details various options for modifying the default run state of the application.

update EB docs to include new config options from JClarke and upgrade version numbers.  also adds a TOC at the top because there are several sections to that page now.

From https://support.google.com/a/answer/176600?hl=en when using port 465, the security protocol should be SSL, not TLS, which corresponds to port 587.

Documents changes made in #1370 that resolves #1332