Http admin page for swarm nodes

[gbalint]

Closely connected to the status page issue #158

The difference from the status page that the admin page should be interactive: it should contain parameters which can be updated.

It doesn't necessarily has to be a separate page from the status page.

Examples

• update storage size
• upload file

Possible issues

Some parameters are not updatable on the fly in the swarm implementaion. So this issue is not just ui development, some refactoring is possibly needed in swarm too.

We have take care of security, perhaps there is an "internal" domain, for example bzz://upload.internal and bzz://status.internal (a bit like chrome://settings/)

[gbalint]

Maybe we can integrate with the geth dashboard: https://github.com/ethereum/go-ethereum/tree/master/dashboard