abstract predictAR lookback and make it adjustable
fix parentheses to keep code unchanged when lookback=1
predictAR bug fixes
lookbackTime = FORTY_TWO_MINS when lookback=1
change predictAR lookback from 1 to 2 (5m to 10m)
Merge branch 'dev' into wip/predictARLookback
Merge branch 'dev' into wip/predictARLookback
Merge pull request #194 from nightscout/wip/predictARLookback

predictAR lookback abstraction