Client: Handle unusable apps (uninitialized or without permissions)

[sohkai]

If a user installs an app instance that is uninitialized (usually accidentally) or has an instance that has no permissions assigned, we should warn the user about it and let them know what they need to do before it can be "re-activated".

One thought is to place these uninitialized app instances in an area of the App Center, that holds uninstalled or otherwise usable app instances (either uninitialized or without any permissions assigned), and can guide the user as to why they're disabled. Note that a blocker for #575 is where to place uninstalled apps.

We may also want to consider filtering these unusable apps from the side panel, so that only usable apps are available to run, as it would be confusing for users to attempt to use an uninitialized app, and more difficult for app developers if they had to build UIs to reflect this state (we currently do not handle this case).

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@aragon/wrapper can provide most of the information required for an Aragon client to know if an app is usable or not; we can check for initialization, and look up the permissions.

[lkngtn]

It would be great if you could use permissions app to add permissions to an app that doesn't currently have any ACL entries.

Currently you must create the first permission from the CLI and then can do the remaining permissions from the permissions app.