Version 1.4.0 release candidate 1

• Rename an appliance if the default name is already taken
• Existing image option should be hidden when none is available
• Warn users about the need to uncompress the image
• Fix crash when you have no qemu vms and use gns3a
• Change sentry key
• Fix format_exception() missing 2 required positional arguments: 'value' and 'tb' in topologyFile
• Fix dialog box not returning their result
• Log to console the Qt Message Boxes
• Drops securecrt.vbs