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

The test_login test from TestUltraProvider would fail in Python 2.7
due to the dictionary insertion order not being preserved in 2.7
and early 3.x versions. Comparing the dictionaries containing the
query parameters solves this. Snippet from test failure:

- username=user&password=rightpass&grant_type=password
+ grant_type=password&username=user&password=rightpass

Due to an import error the envvar source tests would not run
in Python 2.7

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.