Theming: set the sidebar color#16

Description
When I am viewing my wiki
I want to be able to see a sidebar that matches my project.
So I can feel like it matches my wiki/product theme.

Current behaviour
No way to set sidebar color

Expected behaviour
Way to set sidebar color.

Nolt has a great example of this using the gradient.
Will have to handle how text color works with this.

can the wiki just inherit the chrome theme like the one i use?

be able to change the color to corporate color and add logo is a must

Custom sidebar color is now available for pro users.

@Andrés Mangas Jiménez There is a ticket open here for custom logo https://ynaw.nolt.io/79