scm_adapters/git: Raise exception for missing data.
views/deploy_notification: Some default values.
views/deploy_notification: Properly handle newlines.
brief_mail/config_adapters: Accept config if it responds properly.
mailer: Refactor, proxy ActionMailer implementation.
error: Add (BriefMail::Error).
scm_adapters/git: Gracefully handle missing info.
scm_adapters/git: Refactor, cleanup.
views/deploy_notification: Commit log + diff stat together.
views/deploy_notifiation: Fix trailing newline for log output.