Remove unused method JobQueue.AddNode
Remove unused method JobQueue.AddNode

Given that LuxiD now keeps track of which nodes
belong to the cluster, there is no need for the
python job context to be able to change this set.

Signed-off-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>
Reviewed-by: Petr Pudlak <9d19625f8ee825a2c398462ed335cbcf98f79c32@google.com>

ganeti/ganeti,andir/ganeti,leshchevds/ganeti,leshchevds/ganeti,onponomarev/ganeti,onponomarev/ganeti,andir/ganeti,mbakke/ganeti,bitemyapp/ganeti,andir/ganeti,grnet/snf-ganeti,mbakke/ganeti,yiannist/ganeti,mbakke/ganeti,ganeti/ganeti,yiannist/ganeti,leshchevds/ganeti,yiannist/ganeti,bitemyapp/ganeti,grnet/snf-ganeti,ganeti/ganeti