Merge pull request #382 from apoloval/task/prevent-self-cross

Detect self-crossing orders in order submission form
Use multiple peers for the trial testnet
Recover from temporary seed peer address resolution errors

To do so, move PeerGroup configuration to the BitcoinPeerActor and make
DNS resolution part of the connection process.
Merge pull request #383 from sortega/peers

Use multiple seed peers and fix seed peer resolution
Improve test at BlockchainActorTest

It is randomly failing at the nightly and we will know the next time it fails whether the TX is
actually confirmed but not notified or not confirmed at all.
Merge pull request #384 from sortega/improve_test

Improve test at BlockchainActorTest