UI improvements

This issue concatenates several small issues that are automatically handled when implementing ESSENTIALS-293. This issue is retained to check if all is covered.

From ESSENTIALS-182:

• I do not think it is intuitive to use the Hippo logo as a link to the home page of essentials. (I thought it would lead me to the Hippo (onehippo) home page)
• The look of the title can be improved.
• There should also be a label shown that says something like "this page gives you an overview of installed plugins"
• Each plugin should have a description. For example what gives the Events plugin? - What does the content blocks plugin do?

From ESSENTIALS-238:
As a developer, I want to see the Essentials version number. Please show it in the dashboard somewhere.