Turn `check_moving_average_bias_ratio` to classmethod.
Update version to v0.5.5
Add `test_CKMAO_classmethod` into test_unittest.
Merge branch 'CKMAO-classmethod' of github.com:toomore/grs into v0.5.5rc
Update docs.
Merge branch 'v0.5.5rc' of github.com:toomore/grs