Oses and nodes distribution report POC

* doc_type 'installation_struct' renamed to 'structure'
* mapping for doc_type 'sturcture' in the index 'fuel' added
* tox handled
* nodes distribution report fixed
* mapping tests added
* license text added into files
* ranges nodes report implemented
* custom analyzer for lowercased unsplitted values added

Blueprint: send-anon-usage
Change-Id: I26ab5d176d9a6cbcb1f5f12f7c2f50fadc942433