rename seriesElementWidth to timeIntervalWidth, add to bar series and use d3.functor
Merge branch 'master' of https://github.com/ScottLogic/d3-financial-components into seriesElementWidth

Conflicts:
	components/series/candlestick.js
	components/series/ohlc.js
	components/utilities/timeIntervalWidth.js
Merge pull request #173 from tlsim/seriesElementWidth

Series element width