Metrics-graphite does not notify when graphite server is unreachable

Currently there is no notification when Graphite/Carbon server is unreachable for Graphite Reporter.

When Graphite.connect() is trying to connect to a Graphite/Carbon server at an unreachable host it throws NullPointerException.

Right now metrics uses the following code to connect to socket:
socketFactory.createSocket(address.getAddress(), address.getPort());
where address is of type InetSocketAddress.

However there is another method in SocketFactory that takes host as String instead of InetSocketAddress SocketFactory.createSocket(String host, int port). This method would throw javax.net.UnknownHostException (which extends IOException) in case the host is unreachable.
UnknownHostException is a subclass of IOException and therefore it will be handled by GraphiteReporter.report() and logged as warning.