switches to filebased.EmailBackend by default in base settings; adds support for LOG_ROOT to all environment settings so that EMAIL_FILE_PATH can point to the same place in a DRY way
ensures prod settings still use smtp to send mail
switches AWS SMTP server (SES) port to 587 to troubleshoot send mail hang issue
changes QA email settings to use AWS smtp server instead of file backend
SMTP port set to 587 for AWS servers, remains 25 for prod and local
Merge pull request #52 from Harvard-University-iCommons/feature/smtp_port_change

Email backend updates