Fixes bug 1241467
Narrow-casting statistical aggregates to int before inserting
into the resource usage line charts had the effect of unnaturally
smoothening the trend. This was especially apparent for meters
defined over a narrow range (such as cpu_util ranging from 0.0%
to 100.0%).
We now maintain floating point precision for these data.
Change-Id: If6141a4f66aa0078d38aa9f53d913aca5684ad94
(cherry picked from commit 4b973c2fb4)