Remove exclude filtering from test-jars

Remove the filtering from test jars so Maven works in the same way
as eclipse. Test jar filtering has now been setup on the CI server
to prevent them from being published.

Fixes gh-754
Add docs to default build

Add spring-boot-docs to the default profile so that imports by default
into eclipse.
Resore code formatting
Add maven implicit plugin group ID

Add previously implicit <groupId>org.apache.maven.plugins</groupId>
to plugin declarations.