v1.5.0

• Updating to Django 2.0.13, first step towards updating to a recent LTS release
• Updating various dependencies for Django 2.0.13
• Major frontend performance improvements (better caching, script/style include refactoring)
• Backend performance improvements (switch DB mode to WAL)
• Fixed issue with concurrency when updating emails resulting in multiple sends
• Properly collecting static files for plugins and admin files
• Added maintenance mode page for production server