Polish module ordering
Polish profile ordering
Upgrade maven-plugin-plugin to 3.3
Move more repositories to generated settings.xml
Add repositories section to dependencies POM

Add a repositories section to the spring-boot-dependencies POM but
strip it out during a CI build. This allows snapshot and milestone
BOM imports to be used but doesn't pollute published POMs and doesn't
prevent a fresh checkout from building.

Fixes gh-1413
Update travis CI configuration