use options object argument in nodes()

include limit and indexedValue in options
tests work with new metadata format
update test/store to use new node() implmentation

uses options object
no longer require epochmeta as a test dependency

this dep creates an unstable environment since it
is linked by git repository.  ie:  tests for treedb
break when the epochmeta repo is updated, which is
not the desired behaviour.

the test metadata scheme will be duplicated in the
test directory.
use local metadata scheme
add metadata scheme
add parents method