SSDM-1174 byExperiment is now a policy

.../systemsx/cisd/etlserver/IArchiveCandidateDiscoverer.java

...cisd/etlserver/plugins/AgeArchiveCandidateDiscoverer.java

.../ch/systemsx/cisd/etlserver/plugins/AutoArchiverTask.java

.../server/plugins/standard/archiver/ByExpermientPolicy.java

.../plugins/standard/archiver/grouping/DataSetTypeGroup.java

...gins/standard/archiver/grouping/DatasetListWithTotal.java

...r/plugins/standard/archiver/grouping/ExperimentGroup.java

...ic/server/plugins/standard/archiver/grouping/Grouper.java

...rver/plugins/standard/archiver/grouping/ProjectGroup.java

...c/server/plugins/standard/archiver/grouping/TreeNode.java