Handling points from outside of domain in Ordinal scale.

Close #1135.
Merge branch 'develop' into outside_domain

Conflicts:
	plottable-dev.d.ts
Add copying orignal draw steps.
Add defined for y scale.
Do not render only null & undefined.
Merge branch 'develop' into outside_domain
Resolve merge issue.
Merge pull request #1175 from palantir/outside_domain

Handling points from outside of domain in Ordinal scale.