Restructuring of Cypher manual builds

* Move cypherdoc from manual to community/cypher/docs and renamed it to graphgist
* Move uniqueness graphgist from manual/src/cypher into community/cypher/docs/cypher-docs
* Add a import tutorial as a graphgist
* Add //file: to graphgists so local files can be used
* Moved existing graphgists to live under community/cypher/docs
* Graphgists: Added public URLs as a argument for publicly available files