#SB-120: Assign ports to the maven-jetty-plugin, derby-maven-plugin and unboundid-maven-plugin by reserving free ones with the build-helper-maven-plugin

Polished the fix for the strongbox-authentication-* modules.
Merge pull request #6 from strongbox/SB-120

#SB-120: Assign ports to the maven-jetty-plugin, derby-maven-plugin and unboundid-maven-plugin by reserving free ones with the build-helper-maven-plugin