Improvements

• SMS templates now support preview images. Simply provide /sms_templates/:id/preview.png as the source of an img HTML tag.
• Campaigns now support preview images. These render all email and SMS templates within the campaign. Provide /campaigns/:id/preview.png as the source of an img HTML tag.

Bug fixes

• Fixed issues where email template preview images would not render the full height of the image. Preview images now include the full height of the template