EMS: Baguettte Client, Common: Moved EMS client/Netdata recovery code from 'baguette-client' to 'common' package to make it available to EMS server too. Added 'SshClient' and 'SshClientProperties' interfaces in order to generify client recovery code. 'Sshc' and 'BaguetteClientProperties' classes in baguette-client are now implementing the new SshClient and SshClientProperties interfaces. Added purging of failed node addresses from NetdataCollector's ignoredNodes list, when Client Configuration is updated (it contains the nodes without EMS client). Few minor improvements.