Create a suitable error page if the configuration does not exist

[marsson]

As a system administrator, I want to get a comprehensive error if I place an invalid configuration reference on the calendar properties.

Technical notes:
On story #9, we created a property called Calendar configuration name that have to be set for the calendar to work. If the value is invalid, display an error illustration and let the user know what is wrong https://www.lightningdesignsystem.com/components/illustration/