cron job check_ip update datestore w/o updating memcache

[yachang]

Which cause data discrepancy, and in the next minute, check_status cron job will use memcache to revert what check_ip did.

[nkinkade]

There is code in the class IPUpdateHandler to update memcache too.

https://github.com/m-lab/mlab-ns/blob/master/server/mlabns/handlers/update.py#L268

Are you saying that the code just isn't working (which is possible).

Also, is it possible that this issue is essentially a duplicate of #97? If so, maybe we close this issue and add further notes to #97?

[kokosta]

Tasks:

• update all SliverTool for "check_ip" job #133

[yachang]

Fixed by PR #133