Use tasks instead of big fat meta packages

ubuntu-meta is going fater and fater. A lot of people don't use neither lvm nor evms nor mdadm nor hplip nor wifi etc. We should use tasks that are installed as easy as software in g-a-i. There is two kind of task : hardware support and other. Hardware Tasks are installed automatically at install or hotplug. A bunch of Software Tasks should be installed by default. lvm, raid and evms should be installed considering the partitionning scheme created with the partition manager. Other tasks might be installed automatically. Some task might be "core task".

This is an evolution of the task concept currently in debian.