Refactor SmartContractService, remove history polling and add subscription.

[ianadavies]

This PR includes the following changes

• Continuation of service refactor bringing in functionality from apiService into smartContractService

• Create BehaviourSubject for SmartContractHistory

• Removes Polling of SmartContractHistory

• Fixes Issue of SmartContract History not refreshing after creating and calling Contracts

• Fixes calling multiple history requests after deploying Smart Contract