Get rid of Apache Cargo Maven plugin

[pavelhoral]

I propose to get rid of Apache Cargo Maven plugin. This plugin is used to merge WAR based modules openam-server-only and openam-console into openam-server. Due to that openam-server has uberwar as it's packaging definition, which makes extending that project somewhat hard.

Merging WAR modules can be achieved via Maven's WAR plugin overlay feature. The only thing this plugin is not capable of is merging web.xml. So to overcome that maybe we also can migrate to web-fragment.xml.

Benefits:

• Getting rid of unnecessary Maven Plugin.
• Having standard packaging type for the Maven project (instead of uberwar).
• Better support in some IDE (e.g. m2e)

[pavelhoral]

Thing to consider: We might want to restrain from using web fragments as those are usually subject of security checks (e.g. CIS Benchmarks for Tomcat).