Register the rule as a monitor object to expose the available servers count metric for AvailabilityFilteringRule.
Merge commit 'a9c21088afa8d5363a9a21f2fa1c61ffe73e723f'
Merge pull request #13 from allenxwang/master

Register the rule as a monitor object to expose the available servers count metric for AvailabilityFilteringRule.