Update README.md

This was a dead link, could not find a fix for it: 
http://verify.driveshare.org/api/downstream/status/
Merge pull request #18 from kenCode-de/patch-1

Update README.md
Merge pull request #19 from wiggzz/master

Added control for maximum tokens per ip address
added description of tokens per ip enhancement
Merge branch 'master' of github.com:storj/downstream-node
Update verify references to live.
small doc change, and added check sig function
Merge branch 'master' of github.com:storj/downstream-node
Added additional field in status JSON for expiry date of last contract.
PEP8 fix.
More PEP8.
Return None if contract array empty.
This is Python, not JavaScript, bro.
Because 80 columns is just...too...much.
added signing on server side
Merge branch 'master' of github.com:storj/downstream-node
pep8 fixes