Description of problem:
To reflect on several customer issues & suggestions, spacewalk-schema-upgrade
command should be able to display general information on schema upgrades
as well as inform the user (or customer) to make sure a valid db backup exists.

Version-Release number of selected component (if applicable):
Satellite 5.5

How reproducible:
Always

Steps to Reproduce:
1. Run spacewalk-schema-upgrade for a satellite-schema upgrade
2. The command should give a general guidance on schema upgrades
3. The command should instruct to check whether a valid db backup exists
before commencing with the schema upgrade.
  
Actual results:
Not implemented.

Expected results:
Implemented.

Additional info:
N/A