Added missing dependencies

Removed node6 support

Updated to work with async crypto library

6.22.4

try other downloads regions if the first one was alraedy fetched

6.22.3

reuse tree-index across requests

6.22.2

fix randomizer for infinity ranges

fix bit truncation issue

6.22.1

Reduce bitfield footprint (#184)

remove unused stub

6.22.0

do not request remote bitfield if not downloading