Corba aliases

This PR allows to create CORBA component servers that instead of using their own name, use an alias.  This is handy if you have X similar deployments in which you do not want to do component renaming for various reasons but you still want to remotely connect to multiple of them.  In this case registering them under an alias allows you to create remote proxies that remotely will be known under their alias name.  It needs https://github.com/orocos-toolchain/rtt/pull/66 to work.