0.4.0

Changelog:

• Switched to using Docker Compose.
• Droplet: Support for other Docker registries.
• Loading screen for droplet.
• Admin: Added ability to view logs.
• Droplet: Control panel sidebar handle is now movable.
• Login: error message is displayed for invalid password.
• Refactored droplet resource management.
• Droplet: Improved reconnection attempts.
• Fixed left over containers when a droplet had persistence data.