Feature/build transaction

Generate empty addresses when transactions are found 

Adding addresses when transactions are found so that we always have a 20 empty addresses buffer window

- Switched wallet interface to real API data
- Added basic validation
- Updated Angular

Feature/wallet recovery

Wallet recovery work

Changed the create address endpoint to be a get address so that either the last unused address or a newly created address will be returned to the caller

Added getting the balance for the user's accounts

Added get transactions history

Added Tracker object to manage syncing of blocks

- Switch from template driven forms to reactive forms
- Add pipes for coin notation and coin abbreviation (tbc)
- Improve navigation, add lazy loading and back buttons
- Add classes for creation, recovery and loading of wallets
- Various small improvements