Updated Parse2 not to create vector headers with empty domains for enum cols. Now it creates headers with correct domains right away (individual chunks are updated afterwards as before).

This is to avoid hitting bug with stale vector header(Vector header updates in K/V but chunks keep their old header pointers). We do not really update vector header objects as of now elsewhere, so there isno need to solve this right now.

Conflicts:
	src/main/java/water/api/GBMProgressPage.java