Added support for include files filtering

Implements what is discussed here: https://github.com/maven-nar/nar-maven-plugin/issues/15

I've added new IncludePath class to the maven_nar namespace, however there's also IncludeClass inside maven_nar.cpptasks.types but I haven't found any better way.

I've also removed 'type' parameter from createIncludePaths() and merged it with getIncludePaths() since it  looks like 'type' is always MAIN and TEST is never used.

Tested only with GCC under Linux.