Namespace and Host Affinity

[germanramos]

Add the following features:

• Configurable namespace: Use "default" namespace for Replication Controllers (fix) and Services. In addition, you can override the namespace using "-namespace" command line option. There is also a special namespace value "ASK" that causes to put a namespace question in the output rancher-compose.yml so namespace can be chosen when launch from rancher catalog.
• Host affinity support. Convert the label "io.rancher.scheduler.affinity:host_label" to the equivalent affinity syntax for kubernetes. Ignore other rancher cattle labels.