I removed the unecessary plugins from the build and reworked it to use
the ci friendly way of setting the version for releases (see
https://maven.apache.org/maven-ci-friendly.html).

This removes the spring-boot-starter-parent from the build, and
duplicates the necessary plugin configuration in he Spring Boot Admin'
parent instead. This way our BOM doesn't include version for
dependencies managed by boot's BOM

With this commit the support for Turbine is completly revised. From now
on Turbine is supported via a separate module and is integrated as top
level view.

closes #306

closes #299

The 1.4.0 release was a total disaster. Webpack didn't build the css correctly
because of travis using an ancient nodejs version.

Remove the git-commit-id-plugin from the sample and don't fail in docs when the
sources are not located in an git-repository (e.g. downloaded from zip)

I did an accidental release of a 1.3.2, so we need another increment