Version 0.3.0

• Added interests to currency networks

  A trustline now also consists of two interest rates given by the two parties to each other.
  These interest rates are used to calculate occured interests between the two parties. The balance
  including the interests is updated whenever the balance (because of a transfer) or one of
  the interest rates (because of a trustline update) changes. To calculate the interests we
  approximate Continuous Compounding with a taylor series and use the current timestamp and
  the timestamp of the last update.

• Added interest settings to deploy tool

  The deploy tool now allows deploying networks with different interests settings. The current options
  are: Default interests: If this is set, every trustline has the same interest rate.
  Custom interest: If this is set, every user can decide which interest rate he want to give.
  Prevent mediator interests: Safe setting to prevent mediators from paying interests for
  mediated transfer by disallowing certain transfers.

• Close a trustline

  Added a new function to do a triangular payment to close a trustline. This will set the balance
  between two user to zero and also removes all information about this trustline. This is still work
  in progress and might change.