Spacemesh api mock [WIP]

[ImmanuelSegol]

• [x] Post a Transaction
• [x] Get Address Balance
• [x] Retrieving an address transactions
• [x] Buy SMC from exchanges
• [x] Get SMC current price
• [x] Get transaction status by TX id

This is just a draft. I have some questions @avive @iamonuwa :

• Is the general implementation pattern proper, and what you guys where thinking of ?

• Should I add auto-fix to TSlint? And why are there lint rules that wont allow me to use a type for Transaction but instead request a interface

• Could you provide some better mock data and structure for example how should buySMCFromExchange work exactly should it search for the cheapest price on a list of exchanges or should it let the user specify the exchange with some sort of ID?

Closes #28

[ImmanuelSegol]

@avive @samparsky I will make the changes thanks for the review. What else should I improve/add/change?