Add note explaining gradle ResolutionStrategy

Update reference documentation to include a note explaining that
"blessed" versions a chosen based on the gradle plugin version, and
that builds are repeatable.

Fixes gh-619
Document how to customize dependency versions

Add a section to the "how-to" on customizing third-party dependency
versions when using Maven.

Fixes gh-434
Add mvnDebug how-to

Fixes gh-713
Tighten up documentation on SSL and HTTPS

Fixes gh-640