Also add _extra_changes to dynamic record tests to make them more
exhausitve.
Simplify root profile's endpoint names.

If single-value pools have a weight defined, it will be lost by this
optimization. Next time octodns-sync is run, it will show an update for
setting the weight on remote. To overcome this, this commit includes a
change to Record object that ignores the weight in single-value pools.

This change improves the process for checking for AzureDNS zones by using the known set and not relying upon custom error handling.

Since the provider already fetches the zones, octodns doesn't need to make a second call to check for the existence of the zone - _populate_zones already does that for us.

cc #84 #628