Adding API endpoint for endTickHeight in baseAxis

Close #612.
Height recomputed to max(tickLength,endTickLength)
Merge branch 'master' of github.com:palantir/plottable into 612-end-tick-length
Subclasses of baseAxis use maxLabelTickLength

maxLabelTickLength as so: if endTickLabels exist, use maximum of endTickLength, tickLength
If they don't exist, use tickLength
Merge branch 'master' into 612-end-tick-length
using function for maxTickLabel and test cleanup
Merge branch 'master' of github.com:palantir/plottable into 612-end-tick-length

Conflicts:
	plottable.js
	src/components/baseAxis.ts
	src/components/numericAxis.ts
Only use maxLabelTickLength
Modifying test to account for gutter
Adding comments for public variables

END_TICK_MARK_CLASS and adding accidentally removed TICK_LABEL_CLASS
Merge pull request #780 from palantir/612-end-tick-length

Adding API endpoint for endTickHeight in baseAxis