Merge pull request #375 from apoloval/fix/market-info-retries

Fix a bug in `MarketInfoActor` that causes a fail to retrieve market stats
Fix PeerConnection use

Make sure that all peer connections get their close method called and reset connections after a failure.
Reduce logging about blockchain download
Merge pull request #376 from sortega/reset_connections

Reset connections
Refactor MarketSubmissionActor to allow dependency injection

This will ease its independent testing
Introduce submission package

It groups the classes related with order submission and have a
package object for common type aliases.
Move ResubmitTimer to common-akka

This class will be reused from more places
Improve MockSupervisedActor

Now you can use different timeouts when expecting the mock to start/stop
Use a timer instead of ReceiveTimeout in MarketSubmissionActor

Add a new test and simplify the actor states taking advantage of the ResubmitTimer class.
Change abe testnet explorer url.
Merge pull request #378 from gotoalberto/fix_abeurl

Change abe testnet explorer url.
Merge pull request #377 from sortega/market_submission

Fix market submission interval time
Introduce ExpirationTimer

This timer is able to reset its timeout once started as many times as needed
Replace ReceiveTimeout by ExpirationTimer

And fix a problem preventing orders for expiring when receiving a continuous stream
of messages.
Bump bitcoinj version to 0.12.1
Use Option[FiniteDuration] instead of Duration in broker package
Add a sensible timeout to MutablePropertyTest
Introduce a maximum limit of fiat amount per exchange in `coinffeine-peer`

This limit is required to avoid too large orders that would take too much
time to be exchanged.
Make order submission form to check fiat amount not to exceed the limit
Merge pull request #379 from sortega/fix_broker

Fix broker actor handling of order expirations