Tox:
* Add Tox factor for extras (all, none, individual ESP).
For now, only break out ESPs that have specific extra
dependencies (amazon_ses, sparkpost).
* Install most package dependencies (including extras)
through the package itself.
* Use new runtests.py environment vars to limit test tags
when Tox isn't installing all extras.
Travis:
* Rework matrix to request specific TOXENVs directly;
drop tox-travis.
Test runner (runtests.py):
* Centralize RUN_LIVE_TESTS logic in runtests.py
* Add ANYMAIL_ONLY_TEST and ANYMAIL_SKIP_TESTS env vars
(comma-separated lists of tags)
Test implementations:
* Tag all ESP-specific tests with ESP
* Tag live tests with "live"
* Don't import ESP-specific packages at test module level.
(Test discovery imports test modules before tag-based filtering.)
Closes#104
If you are using an SES ConfigurationSet with open or click tracking
enabled, SES replaces non-ASCII characters with question marks as it
rewrites the message to add tracking, if the bodies are sent with
`Content-Transfer-Encoding: 8bit` (which is Django's default for utf8
body parts).
Force potentially problematic parts to use CTE: quoted-printable
as a workaround.
Fixes#115.
