[KARAF-3316] Upgrade to maven-site-plugin 3.4
[KARAF-3317] Upgrade to maven-source-plugin 2.4
[KARAF-3318] Upgrade to maven-surefire-plugin 2.17
[KARAF-3319] Upgrade to maven-war-plugin 2.5
[KARAF-3320] Upgrade to apache-rat-plugin 0.11
[KARAF-3321] Upgrade to build-helper-maven-plugin 1.9.1
[KARAF-3338] Upgrade to Apache POM 15