COMPASS-80 add databases view + collections table

[rueckstiess]

Some larger refactors in this PR:

• move TabNavBar to internal-packages/app (use this as shared components home for now)
• give TabNavBar a dark and light theme
• create a internal-packages/database package, with a single tab "Collections" and a CollectionsTable view
• Change navigation structure so that ./src/app/home maintains the state for navigating between all main views (i.e. not "Connect")
• make databases clickable in sidebar and navigate to new Database view.

Current state: Collections are in a table but InstanceStore doesn't actually contain most information required at this level, e.g. size of each collection. This only happens once we click on a collection. So we need to go and fetch all that info in the store (async.parallel ?)

[durran]

Can you move this into the contructor please? See: https://github.com/10gen/compass/blob/master/src/internal-packages/server-stats/lib/component/databases-table.jsx#L17

The only reason this does work is that the app package is loaded before the database package but the order in which packages are loaded will never be guaranteed and should not be depended on.

[durran]

Just the one thing to address from me then LGTM. If you guys can't get to it today then I'll take care of it.

[durran]

I fixed my own comments, rebased, and pushed the fixes. However...

Was this intentional? The zero state for me is no longer showing the database list.

[rueckstiess]

@durran, this latest rebase + force push messed up my local branch. Could you add the following line in ./src/app/home/index.js at the end of the render() method?

this.switchMainContent('');

That will cause the zero state to go to the "empty" namespace, which is the instance level.