Add forging center

[karmacoma]

Add forging center for registered delegates to view:

• Forging rank, productivity, approval graphs
• LSK earned / forged
• Forged blocks

[slaweet]

To start the discussion on what should the forging center look like I created a branch with some html mockups: https://github.com/slaweet/lisk-nano/tree/23_forging-center

I covered three states, that can be trigered by url parameters when running it on localhost:

• Not a delegate
  http://localhost:8080/#?noforging=true
  

• No blocks forged
  http://localhost:8080/#?noblocks=true
  

• Active delegate
  http://localhost:8080/
  

[4miners]

Looks good, but can we move that to separate page?

[slaweet]

@4miners I agree that there's too much stuff on the page, though I'm not sure how exactly to do switching to a separate page.
Maybe we don't need the "send" form displayed all the time and can move it to a popup dialog opened by a new button like this: