Merge pull request #297 from apoloval/fix/ScalaFxWarnings

Fix all warnings in GUI module
Fix how keys are checked for being able to sign

The old test was producing false positives on the integrated tests.
Make bitcoin implicits easier to use

As done with the currency implicits, make the package object to 
extend the Implicits trait making most usages of the bitcoin package
work with just one import. As an alternative, the Implicits trait can
be mixed in any other class with the same effect.
Merge pull request #299 from sortega/fix_it

Fix how keys are checked for being able to sign
Clear timeouts on TransactionPublisher

This will prevent the actor from polluting the log with messages about
the timeout message being not delivered. Also improve the logging.
Make TransactionPublisher more private
Reduce the log level for BitcoinPeerActor

Blockchain download messages distract when looking at the IT logs.
Pass the right timeout to TransactionPublisher
HandshakeArbiterActor abort on publication error
Merge pull request #300 from sortega/fixes

Improve transaction publication