Add new uptime claculator
Fix uptime period calculation in limit cases and added more tests
Fix bug in populate fixture script

Caused by the fix from 0a397ad0dc66ee5acc14c4d1663839f08086ad65
Make UptimeCalculator more flexible at initialization
Add uptimePeriods to hourly stat records
Add ability to display uptime bars in the dashboard
[refactoring] move ping aggregation logic into QosAggregator class
[refactoring] move hourly and daily aggregation logic into QosAggregator class
[BC Break][WIP] Switch aggregation to the new aggregation framework

Bye, Map/Reduce!
also aggregating uptime intervals for day and month

Warning: Changes all stat models
Warning: Tags are broken, last 24H qos is broken, too
Add period intersection for tags, based on Tree Interval algorithm
Switch storage of intervals to store outages rather than uptime periods.
Restore tag and last24 features
Refactor Aggregator class

Shorter and more meaningful classes
Display uptimeBars in check list, tag list, and stats
Switch uptime bar drawing to absolute div positionning

Avoids rounding issues that would remove smaller intervals and reduce
the overall size of the uptime bar when many small outages appear.
Fix incoherence in pause time in check list
Store one period per day in Monthly stats to avoid storage problems

Storing outage periods for monthly stats would cause growing document
sizes in CheckMonthlyStat and TagMonthlyStat collections
Reorder columns in history table
Refactor outage interval calculation to allow paused intervals

The refactored algorithm makes the merge interval for tags obsolete
Add support for pause intervals in uptime bar script