Improve HTTP /restful/rhizome/bundlelist.json token

Now tokens are included in each row instead of a single token in the
enclosing JSON object.  Only puts tokens on the first row, and
thereafter all rows with a rowid higher than for the previous row that
had a token.
Add Base64URL encode/decode functions
Implement HTTP /restful/rhizome/newsince/.../bundlelist.json

Not tested
Reduce Rhizome SQL trace logging to once per prepared statement