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

In Python 2.7 the if statement would catch both cases from the test
test_populate_lenient_fallback, so the test was failing. These are
the error strings differences between Python 2 and 3:

Python 2:
NoLenient: populate() got an unexpected keyword argument 'lenient'
NoZone: populate() got multiple values for keyword argument 'lenient'

Python 3:
NoLenient: populate() got an unexpected keyword argument 'lenient'
NoZone: populate() got multiple values for argument 'lenient'

Fix typo

Add alt text to images

for example:
`$ octodns-sync --config-file=./config/production.yaml` was throwing an error. Then, when i did `$ octodns-dump`, it prompted me to put it in this format: `$ octodns-sync --config-file CONFIG_FILE` (without the = sign)

Handle re-used pools in Azure DNS dynamic records

Allow the option to not pass Host header in healthchecks

Ensure that dynamic records map to unique Azure TM profiles

minimize Azure Traffic Manager hops for dynamic records

UltradnsProvider: Add support for ALIAS type (fix #644)

Co-authored-by: Ross McFarland <ross@github.com>

Do not trigger change for health checks on cname dynamic records

map Oceania to Australia/Pacific in Azure

Support dynamic records in Azure DNS

Add a validation requiring single value weight=1

Updated doc to reflect config file location for zone wide lenient flag Fixes octodns/octodns#707

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.