always create sequential nodes

this makes it trivially possible to do leader election in synapse.
Revert "begin by reporting the service as down"

This reverts commit 4390e9d6c57f28b28dc7b3fdc7c714553efb1a8f.

Now that we're creating all nodes as sequential nodes, there's no
reason to do this.
Merge pull request #40 from airbnb/sequential_nodes

Sequential nodes