fix html_rewriter missing ; on entities
js rewriter: only rewrite full document.domain
PathIndexPrefixResolver using binsearch on path index, for #9
resolvers moved to replay_resolvers.py
improve path-resolver logic: each resolver returns an array of possible
files (could be from primary or secondary storage).
then, iterate over all possible files from all resolvers until
a successful load, or raise exception if all failed