[#61] Object client PUT relations
[#61] Relations delete
[#61] Very basic relation enumeration

It's a starting point, but still needs:

- Sub-relation querying
- better testing/handling of items outside of main item's collection
[#61] Better tests for kv from other collections
[#61] Allow graph traversal to arbitrary depth
rework Graph to use KV.from_listing
[#61] Relation parallelism
[#61] Docs for KV#relation
[#61] Docs for most of Graph
Disabling ResultsNotReady for in_parallel
wrap up documentation for Graph
disable parallel/enumeration test for now
Revert "disable parallel/enumeration test for now"

This reverts commit a8ce0d9a7751910fbd0bfe5dac580de46e78e59b.
Revert "Disabling ResultsNotReady for in_parallel"

This reverts commit faf25812c8815ff2432baacbf0e538bbb9fd05df.
Lazy enumerators should not pre-fetch results
don't test lazy unless Enumerable has it
Merge branch 'mattly/61-relations'