Added monolog, swiftmailer, and twig.
Renamed to DailyNotifierService
Created Admin class
Newly created SwiftMailer wrapper.
Newly created NotifierInterface
Newly created class: SessionFilterService
Added accessors and mutators
renamed function getSessionBetween and getParticipationRecords.
added functions getSessionExperiment, getCurrentSignupRecords, getParticipationRecords, and getOpenSessionsBetween.