Add Riak manager support for direct 2i->keys lookup.
Fix index lookup, use it for backlinks.
Merge branch 'develop' into feature/issue-527-direct-riak-index-lookup
Require riakasaurus new enough to have the index lookup bugfix.
Use direct index lookup in message store.
Merge branch 'develop' into feature/issue-527-direct-riak-index-lookup
Better comment for sadness in index_vals_for_field.
Fixed better comment for sadness in index_vals_for_field.
Merge branch 'feature/issue-527-direct-riak-index-lookup' into develop