Remove the entity from base

Property definitions

neo4j $ Neo4jClient :: delete_node
	# Remove the entity from base
	fun delete_node(node: NeoNode): Bool do
		if not node.is_linked then return false
		var url = node.url.to_s
		delete(url)
		local_nodes[url] = null
		node.url = null
		return true
	end
lib/neo4j/neo4j.nit:147,2--155,4