added retrieve archive and archive content to controller and tests
fixed path and source to point to the binary path inside the AIP and removed redundant json files from the AIP
introduced new abstraction layer for AIP creation
changed service to archive a whole subtree, but there's still an error when creating the subdirectories in the archive
fixed adding child entities to a parent's archive
Merge pull request #11 from escidoc-ng/archives

Archival features/fixes