Add extra grid view tab

[renaatdemuynck]

Problem Description

When the list of apps is very long, you have to scroll a lot. A grid view tab that is displayed by default could provide a better experience.

Proposed Solution

Add an extra grid view tab at the beginning of the tab list:

Additional Information

Extra sorting options or possibility to reorder would also be handy...

[renaatdemuynck]

I opened /sites/manage.html in the browser and tweaked it a bit to create the mock-up, so I already have the HTML/CSS for this. It's basically the same as for the 'Apps' tab, but with some elements removed and a slightly different CSS. I'm willing to provide a pull request.

[filips123]

This was implemented in #626 by @Hikari-Fox and will be released in the next version.