Fix wrong ckanext-harvest version.

Update image versions in docker-compose files.

[#49] Sync repo with PDND CKAN (#50)

* Make Dockerfile name standard

* Update compose configuration after dockerfile renaming

* Move ckanext-spatial submodule to 188_clean_tags branch

* Add harvesters orgs and sources.

* Setup and testing harvesting
- replace old periodic-* scripts with ckan-harvest one
- add CKAN_HARVEST option in docker-compose
- update readme (harvesting sections)
- update harvesters submodule
- dockerfile cache optimization
- minor fixes

* Ready for deploy on dockerhub
- move solr submodule from teamdigitale to italia
- update docker files
- update README

* Fix dockerfile reference