Expose Raiden Rest API at raiden start

[LefterisJP]

Problem Definition

Currently raiden starts by exposing the raiden command line interface which is not what we need by default.

Solution

Start the raiden rpc server by default instead of opening the command line interface and show an appropriate message to the user.

Tasklist

• Add two new arguments to the raiden executable. These would be console and rpc which would start raiden with the console interface and the rpc interface enabled respectively.
• Remove the command line interface as the detault raiden interface.
• Add an interface that will start the rest api server and provide a message to the user informing him how to connect to and interact with the rest server. Make this the default behaviour.

[LefterisJP]

Closed by #518