Description of a new channel is not used

A user can provide a 'description' when creating a new channel. However, that description is not used at all. It is not even stored in the repository.
We should either remove the 'description' field from the 'create a new channel' dialog, or use the description (i.e. provide it as an additional column in the channel overview).

Steps to reproduce:
1. open the channel overview
2. click 'Add channel'
3. select a blueprint and click 'Next'
4. enter a name, URL, and description for the new channel and click 'Create channel'

Expected: the description is saved, for example in a property 'hst:description' of the node /hst:hst/hst:channels/<channelname>, and available as a column in the channel overview
Actual: the description is discarded

Another (simpler) option is to not ask for a description in the first place.