Do not depend strictly on TSDB connection, but on a TSDB adapter.

To do that, we've created a 'Historian', which is a metric collector. There's a historian for CloudWatch and for TSDB, for now,
and CloudWatch is still to be implemented.

This commit should be seamless and does not change behavior, but now we have a way to plug in different types of metric
collectors.

[#45654133]
Implementing historian for CloudWatch.

[#45654133]
Log data to both AWS and TSDB historians.

[#45654133]
Make AWS historian use EventMachine's threadpool

[#45654133]
Adding aws-sdk and its dependencies to vendor cache

[#45654133]