common config module added
client config updated with common config mixin
server config updated with common config mixin
Fixes Issue 72 - Code duplication between client and server config
--- Duplicate code between core/config/{client.rb|server.rb} is removed by creating a common mixin
    containing the shared code between the two config files

    All server.rb and client.rb code references or instanciation of client and server
    are replaced with global config variable in global_hanlon.rb