Make launcher ignore some files when parsing configuration templates

Currently, it is possible to specify which extensions must be included by the ConfigurationGenerator when parsing the templates. But, even if not parsed, a file is always copied to the server. Provide a way to blacklist some files from the nuxeo.defaults file, based on their extension or based on their full name/path.
The first candidate is nuxeo-distribution/nuxeo-distribution-resources/src/main/resources/templates-tomcat/common-base/nxserver/config/xadatasource-params.ftl.