1) Added a CatalogFlushTimer whose time period is a configurable
int, CatalogFlushTimePeriod. Default time period is 1 min or 60000 ms

2) Moved swapping of CurrentStatsQueue inside CommitToCatalog method

3) Tested the code by posting 3000 stats to 2 instances of the service.
At the end of posting, Each instance had around 500 items in memory
since each catalog item holds a 1000. But, after a min (flush time period),
the items in memory were successfully flushed