v2.4.0

• Decoupled template engines from notifier. (HandlebarsEngine at the moment).
• Added SocialLinkRepository interface.
• Added default (generic) repositories.
• Added mock repositories.
• Added Helpers.
• Added Filters.
• Added Transformers.
• Wrapped the javascript-sdk storage classes.
• Fixed the issue with SignatureGenerator.
• New Datasource:
  • mongodb
  • mongoose
  • dynamodb
  • pg
  • mysql2
  • sequelize
• New Notifiers:
  • Twilio (SMS)
  • Vonage (SMS)
  • SendGrid (Email)
  • SES (Email)
  • Mailgun (Email)
  • Mandrill (Email)
  • Nodemailer (Email/SMTP)
• New Event Channels:
  • Redis (Pub/Sub).
• More Fixes.