* Match other ESP test strategies for
test_mandrill_backend and
test_mandrill_integration
* Extract test_mandrill_session_sharing into
SessionSharingTestCasesMixin for all
requests-based ESP backends
* Move leftover Djrill feature tests into
test_mandrill_djrill features (until they are
handled as part of esp_extra or in normalized
ESP template/merge features)
Closes#7