* Update utils.get_anymail_setting to support
kwargs override of django.conf.settings values
* Use the updated version everywhere
* Switch from ImproperlyConfigured to
AnymailConfigurationError exception
(anticipates feature_wehooks change)
Closes#12
Interpret dates and naive datetimes as Django's
current_timezone (rather than UTC like Djrill did).
This should be more likely to behave as expected
when running with a non-UTC TIME_ZONE setting.
(Prep for installing backends as package extras)
* Extract AnymailRequestsBackend and RequestsPayload
to base_requests.py
* Don't define/require requests exceptions when requests
not available
For MANDRILL_API_KEY (e.g.,), look for these settings:
* ANYMAIL = { 'MANDRILL_API_KEY': '...' }
* ANYMAIL_MANDRILL_API_KEY = "..."
* MANDRILL_API_KEY = "..."
(the "bare" third version is used only for settings that
might be reasonably shared with other apps, like api keys)
