S2I builds take too long

Running S2I takes several minutes even for simple projects, even if using a local Maven mirror (using MAVEN_MIRROR_URL env variable)

There are several reasons why it takes so long.

1. Using io.fabric8:fabric8-project means maven needs to download a lot of POM files sequentially. A proper product BOM file with a simpler structure would reduce the number of POM files needed to be sequentially downloaded.
2. Maven plugins used in quickstarts use duplicate dependencies with multiple (but similar ) versions of the same artifacts
3. Some of the plugins are run even if they are not needed in S2I builds (at least fabric8:json)
4. Common maven plugins (such as compile, jar, etc.) and their dependencies are downloaded at build time. They could be included directly in the S2I image (as they will be downloaded anyway in 99% of the builds) Alternatively, there could be a documented and supported mechanism to enable users to extend the fuse image to put their common dependencies inside their inherited image without having to change the s2i scripts.