#3 empty project state

[phoenixbox]

What's this PR do?

Adds empty project state for first time users, with mock placeholder cards generated to give the impression of what a full Kanban board would look like. It prompts them to add an item.

Where should the reviewer start?

placeholder-cards.js

How should this be manually tested?

mock the state.items collection on:

views/compnents/item-column/index:109 so that the empty state can be simulated

What are the relevant tickets?

#3

Screenshots (if appropriate)

[wookiehangover]

"looks good to me"

let's merge once those logs are removed

[phoenixbox]

@wookiehangover :+1: updated