Fix IE test failures caused by Time Axis tests choking.

Time Axis tried to set text-anchor to "left", which isn't a valid
value.
Merge pull request #762 from palantir/fix-ie-tests

Fix IE test failures caused by Time Axis tests choking.
Merge branch 'master' into typescript-impatient

Conflicts:
	plottable.js
	test/tests.js