tanodb getting preflist

ring.erl.converted.for.tanodb.mark

```
Calc = fun(Bucket,Key) ->
BKey = {Bucket,Key},
{ok, Ring} = riak_core_ring_manager:get_my_ring(),
DocIdx = riak_core_util:chash_key(BKey),
NValue = 1,
UpNodes = riak_core_node_watcher:nodes(tanodb),
Preflist2 = riak_core_apl:get_apl_ann(DocIdx, NValue, Ring, UpNodes),
[Res] = [Part || {{Part,Node}, Type} <- Preflist2],
Res
end.

Calc(<<"d">>, Key = <<"e0c97a4cde6c">>).
```

Great, that worked, lets back up and get access to the ring again. 

```
{ok,{_,_, _, {RingSize, NodeList}, _, _, _, _, _, _, _ }} = riak_core_ring_manager:get_my_ring
().
```
That returns a lot of data, but we are only interested in the nodelist. 
Let's take a look a the head of that list.

```erlang
(tanodb3@127.0.0.1)66> [H|_] = NodeList.
(tanodb3@127.0.0.1)65> H.
{0,'tanodb1@127.0.0.1'}
```

Ok, from that lets extract the partition list.

```erlang
(tanodb3@127.0.0.1)63> Partitions = [ Part || {Part,_} <- NodeList].
[0,22835963083295358096932575511191922182123945984,
 45671926166590716193865151022383844364247891968,
 68507889249886074290797726533575766546371837952,
 91343852333181432387730302044767688728495783936,
 114179815416476790484662877555959610910619729920,
 137015778499772148581595453067151533092743675904,

```

Lets create something for generating random numbers:

```
(tanodb3@127.0.0.1)89> integer_to_list(round(random:uniform() * 10000000000000000000000000000000)).
"1421082177012422726572125978624"
```