de18f11 Added a 'min_periods' parameter to the 'PositiveSpikeTest' class and the 'NegativeSpikeTest' class.
eb871c7 Added the 'BeforeNaNTest' and the 'AfterNaNTest' to 'tests.py'. Added these two tests to the 'demo_program.py'.
8d15200 Added information on setting the limits in 'README.md'

git-subtree-dir: autoqc
git-subtree-split: de18f11ff5b7b59230960615942c93a7a308022d