Refactor value transfer logic (#330)

* Feat: value transfers are working

* Feat: tangle now detects invalid transactions

* Refactor: refactored some code

* Feat: finished unit test for value transaction

* Feat: added ledger state (reads information from value tangle)

* Refactor: refactored some code

* Feat: finished refactoring isTransactionSolid method

* Feat: added RealityId model for parallel reality based ledger

* Refactor: moved Output to tangle and introduced branches

* Refactor: refactored some code

* Refactor: renamed "NEW" color

* Feat: started adding branches

* Feat: nothing works anymore :p Started to refactor

* Feat: cleaned up tangle in valuetransfers

* Fix: fixed most refactor related bugs

* Feat: introduced branchmanager and utxodag

* Refactor: cleaned up some code

* Feat: introduced ledgerstate

* Feat: balances get booked into branches

* Feat: started implementing fork logic

* Feat: added some more logic :P

* Feat: commit before develop rebase

* Fix: fixed comments from golangci-lint

* Refactor: refactored moveTransaction logic

* Refactor: refactor

* Refactor: refactored valuetransfers to be a selfcontained app

* Fix: fixed errors due to merge

* Fix: fixed bug

* Feat: added preferred/liked to branch

* Feat: added a lot of branchmanager logic

* Feat: implemented FPC in the valuetransfers DAPP

* Refactor: refactored according to golint