Improve CI build process for speed and backward-compatibility testing

[sapessi]

• Implementations: All

Scenario

Currently, the build process is executed in Travis by a single shell script (travis.sh in the root of the repository) and it sequentially builds all framework implementations, archetypes, and samples. There are two challenges with this approach:

• The build process is slow
• We do not test against older versions of frameworks that should technically still be supported

Expected behavior

Split each framework build into a separate build process so that they can be executed simultaneously. Also, take advantage of property overrides in maven (-Dspring.version=4.3.25.FINAL) to run each framework build and test multiple times, against each version of the framework that should be supported