UI/UX Improvements - Custom Database Page

[pverscha]

• We should update the error message for Docker on the custom database page. If no connection can be made to the Docker Daemon it currently shows an information dialog asking the user to start docker, but we should also inform the user that Docker needs to be installed before custom databases can be constructed.
• On this page we should also explain what a custom database is and how one can be constructed.
• Logs toggle button needs to be changed into a text-button and should be placed above the logview, not next to it.