OpenTSDB/opentsdb — pull request #189 by oozie (2013-06-03 21:27:04+00:00)
Title: Fixing #149 - helper class bug in StdDev test

- Fixing a bug in `hasNextValue()` method of a helper used in the test,
- Added 2 tests for extreme cases in calculating standard deviation.
- Tightened the error margins for roundoff errors (leaving more than enough wiggle room).