improve cluster meta test coverage in cluster_meta_basic
cluster meta simulation test

this test is not meant to be part of the main riak_test giddyup suites
but it is useful for measuring certain properties of cluster metadata.
export wait_until/3. needed by cluster_meta_rmr
Merge pull request #450 from basho/jrw-more-cluster-meta-tests

Improvements to Cluster Metadata Tests