Add Akka specific config for CI environment

These config files provides specific settings to those projects using
Akka in order to dilate the timeouts on heavily loaded machines (e.g.,
Jenkins server).

The specific config files may be used by passing the argument
`-Dconfig.resource=application-ci.conf` to sbt.

This fixes bug #104.
Make handshake arbiter notify the tx parts

This change makes the handshake arbiter responsible for all 
communications with the parts entering in an exchange.
Merge pull request #110 from apoloval/issue/104

Add Akka specific config for CI environment
Merge pull request #111 from sortega/feature/integrate_arbiter

Make handshake arbiter notify the tx parts
Add SellerExchangeActor
Use context.stop instead of PoisonPill
PR feedback
Merge pull request #112 from edrevo/add-seller-exchange-actor

Add SellerExchangeActor
Make BuyerExchangeActor to receive initialization message
Make HandshakeActor to receive an initialization message
Make PeerActor to receive an initialization message
Make MessageGateway to receive an initialization message
Make HandshakeArbiterActor to receive an initialization message
Remove wrong test

Remove "Protobuf RPC Message gateway should throw while forwarding
when recipient was connected and then disconnects" as the test wasn't
asserting that in the first place and when tried to assert that I've
realized that ProtoRPC calls don't throw an exception that can be
wrapped into `ForwardException`.
Merge pull request #114 from sortega/feature/simplify_cake

Simplify cake pattern by using initialization messages
Refactor BrokerActor

Make BrokerActor
 
 * Use an initialization message
 * Extract timeout managing logic to ExpirationSchedule class
 * Move magic number to ProtocolConstants
 * Make traded currencies a configurable value
Use GatewayProbe on BrokerActorTest
Add scoverage plugin
Exclude generated sources from coverage and add some tests
Merge pull request #115 from sortega/feature/simplify_cake_2

Refactor BrokerActor to simplify cake pattern