Description of problem:
Sometimes, a parent channel can have a lot of subchannels.
In that case, when one wants to subscribe to lot of them, one
must manually check in every check boxes.
This is not user friendly.
Some Web2.0 sites (eg: gmail) enable to select many check boxes at once:
- check in the first check box
- press <shift>,
- check in the last check box
Having that feature in the RHN satellite would be good

Version-Release number of selected component (if applicable):
Using RHN Satellite version 5.4.0

How reproducible:
Everytime

Steps to Reproduce:
1. install & register a new machine
2. look at it channel subcriptions
   eg: https://myserver.com/rhn/systems/details/SystemChannels.do?sid=XXXXXXXXXX
3. try to subscribe to all channels
  
Actual results:
It's hard to do, one must manually select all channels

Expected results:
It should be easy (and users are expecting it to be due to their previous experience with eg file browsers or web2.0 apps) to select several channels at once

Additional info: