Introduce PeerGroupComponent

This component provides the strategy for joining the bitcoin network.
In the case of the IntegrationTestNetworkComponent the strategy is just
joining one of our miners and no more peers.
Make coinffeine peer actor use an initialization message
Merge pull request #86 from apoloval/okpaymock-updating

Add balance updating functionality to OKPay Mock backoffice
Fix some issues in config files

* Fix the endpoint setting for OkPay to use the instance in `dev.coinffeine.com`.
* Use the ID and token for the first wallet that will be created by OKPay Mock
* Fix the hostname used by OKPay Mock to avoid binding issues.
Make BitcoinPeerActor to supervise the WalletActor
Make BlockchainActor to receive the blockchain upon initialization
Make BitcoinPeerActor responsible of creating the wallet
Don’t expose the peer group on the component traits
Merge pull request #87 from apoloval/okpaymock-updating

Fix some issues in config files
PR feedback
Merge pull request #88 from sortega/setup_bitcoinj

Setup bitcoinj on BitcoinPeerActor
Fix some config properties

Broker hostname was wrong, wallet key is updated after resetting the testnet
and OKPay Mock endpoint is fixed.
Merge pull request #89 from apoloval/fix/config

Fix some config properties