Fix animations for Line and Area Plots.

Lines were animating from the top of the chart due to an oversight
(we didn't scale the zero value). They now correctly animate from 0,
or from the closest edge of the chart if zero is not in the y domain.

Area charts were updated too so that the line and area would render together.
Remove XAxis and YAxis.

References have been updated to Abstract.Axis or Axis.Numeric where appropriate.
version.ts added, Plottable.version is a thing
Backport a unit test from SLATE-163 to Plottable
Protect/privatize methods addEllipsesToLine and breakTextToFitWidth.
No QE needed, rename & unit test only
Merge branch 'master' into remove-X-Y-Axis

Conflicts:
	test/components/axisTests.ts
	test/testReference.ts
	test/tests.js
Merge pull request #664 from palantir/remove-X-Y-Axis

Remove XAxis and YAxis.
Merge pull request #670 from palantir/remove-unused-text-functions

Protect/privatize methods addEllipsesToLine and breakTextToFitWidth.
remove grunt-contrib-copy
Merge pull request #667 from palantir/slate-163-test

Backport a unit test from SLATE-163 to Plottable
verision.ts moved higher up in reference.ts
Merge pull request #665 from palantir/version-number

Plottable.version added
Merge pull request #647 from palantir/634-line-animation

Fix animations for Line and Area Plots.
Merge branch 'master' into 601-remove-and-detach

Conflicts:
	plottable.d.ts
	plottable.js
	src/components/axis.ts
	test/components/axisTests.ts
	test/tests.js