Support --namespace flag in addition to --ns

[corneliusweig]

The kubernetes CLI standard is to use -n/--namespace for defining a namespace. Kail should therefore also support --namespace in addition to --ns.

[renan]

Following the same flag names from kubectl would make a smoother transition!

[corneliusweig]

Not only the transition. It reduces the mental overhead when using this plugin. Because you don't have to be aware that kail is different from everything else.