Add IT for skipper shell commands

[onobc]

The following Skipper shell command scenarios should have IT coverage:

Command(s)	Expect
help	displays skipper extended help
--spring.cloud.skipper.client.url=foo.bar help	displays skipper extended help
``	goes into interactive mode
--spring.cloud.skipper.client.foo=bar	goes into interactive mode
package list	displays packages
--spring.cloud.skipper.client.foo=bar package list	displays packages