Add ja_variables, update JOBAGENT definition, add --nobest to yum update

Commits:

• ce-image: add --nobest for yum update
• processes: Add ja_variables and update JOBAGENT

Add ja_variables and update JOBAGENT in the processes db. Add --nobest for yum update -y (otherwise the ce-image building process will fail).

These changes were tested using jalien/50056ee0.

Signed-off-by: Elena Mihailescu maria.mihailescu@upb.ro