Allow grouping UI Patterns for better organization

[jigarius]

On the pattern library page, all patterns appear as a flat list. It will be great if there was support for:

• group: A single value – name of the group to which the pattern belongs. Ex: atoms, molecules, etc. or Group A, Group B, etc.
• tags: Multiple values – tags for categorizing patterns. Ex: Card, Clickable, etc. This is not necessary as such, but this can open doors for other functionality in the future. For example, on my site, I have a tag called views row style and I can show all patterns with that style on particular views settings.

[DuaelFr]

I like this feature! We could split it in two parts as the group part seem quite easy to implement (it could work like module's packages)