Consul allows orphaned checks that are not associated with any service

[preetapan]

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When filing a bug, please include the following:

consul version for both Client and Server

Client: 0.8.5
Server: 0.8.5

Reproduction steps

Log Fragments or Link to gist

May 16 06:30:09 ...:     2017/05/16 06:30:09 [WARN] consul.fsm: EnsureRegistration failed: failed inserting check: Missing service registration ```

This is due to a race between removing a service (which also removes associated checks) and adding a check for that service. When these orphaned checks get persisted and get replayed upon startup they repeatedly log the warning shown above and clog up logs.