Restric which records can go into a view

No record can exist in a view that doesn't also have an NS record. No NS record shold be allowed to leave a view if records are also present in a view. This patch attempts to address these edge cases.
Fixed shitty race condtion

This is a symptom of crappy schema design, probably.
Merge branch 'bug_mystical_race_condition' into moz_inv2

Conflicts:
	mozdns/api/v1/api.py