Release of 1.4.9

- 53de87400e62f3e5fd32559ad2384cbfdd5c8194: Merge pull request #799 from mattrjacobs/fix-rolling-percentile-write-thread-safety
- 2639ce4e60818e1710835111e990035d2d2e6b8a: Fix to only get an interval histogram once per recorder
- 65ab2335ea0abca58a87142ef0fcb86c9bc9b8ce: Unit test demonstrating unsafe usage of IntCountsHistogram on write path, and fix
- d0652087c7cdafc2e9f86dad7ee13f3778f5c311: Update CHANGELOG.md
