Improve 'debug.io' fdqueue.c debug logging
Add HTTP server pause response function
Rhizome list cursor 'rowid_since' semantics

Setting 'rowid_since' now causes the cursor to iterate over bundles
in chronological order (oldest first) from that rowid upward.
Implement HTTP /restful/rhizome/newsince/.../bundlelist.json

Now functions as per requirements, blocks for 60 seconds sending
new bundles as they appear, sends new token with each new bundle.
Tested manually.