pkg: add basic StringSlice test
pkg: add basic StringSlice test

jonboulle/fleet,bviswana101/fleet,jonboulle/fleet,dalbani/fleet,endocode/fleet,dalbani/fleet,dongsupark/fleet,coreos/fleet,improbable-io/fleet,mookjp/fleet,giantswarm/fleet,paveltiunov/fleet,giantswarm/fleet,webwlsong/fleet,endocode/fleet,jonboulle/fleet,webwlsong/fleet,esatterwhite/fleet,improbable-io/fleet,flandr/fleet,giantswarm/fleet,thepwagner/fleet,WPMedia/fleet,flandr/fleet,bviswana101/fleet,WPMedia/fleet,dongsupark/fleet,paveltiunov/fleet,improbable-io/fleet,mookjp/fleet,octoblu/fleet,thepwagner/fleet,dalbani/fleet,coreos/fleet,endocode/fleet,dongsupark/fleet,coreos/fleet,octoblu/fleet,esatterwhite/fleet