tests: add rkt rmimage functional tests.
tests: add rkt rmimage functional tests.

This tests should check that images are removed from the store only when
unreferenced by any pod.

intelsdi-x/rkt,cab105/rkt,blixtra/rkt,mattthias/pkg-rkt,monstermunchkin/rkt,coreos/rkt,Shashwatsh/rkt,lucasallan/rkt,mjg59/rkt,ChengTiesheng/rkt,jjlakis/rkt,fdserr/rkt,jasonchaffee/rkt,michelangelo13/rkt,lucasallan/rkt,jonboulle/rkt,endocode/rkt,iankronquist/rkt,iaguis/rkt,blixtra/rkt,iankronquist/rkt,Yhgenomics/rkt,yifan-gu/rocket,dgonyeo/rkt,jzelinskie/rkt,lee212/rkt,endocode/rkt,monstermunchkin/rkt,rkt/rkt,alban/rkt,squeed/rkt,chrisseto/rkt,MattDees/rkt,smarvin/rkt,sgotti/rkt,achanda/rkt,jakon89/rkt,sgotti/rkt,cab105/rkt,mike1729/rkt,ybubnov/rkt,rot26/rkt,tv42/rkt,sstabellini/rkt,intfrr/rkt,luebken/rkt,jzelinskie/rkt,markllama/rkt,kinvolk/rkt,tmrts/rkt,jjlakis/rkt,sstabellini/rkt,intfrr/rkt,il9ue/rkt,iaguis/rkt,crawford/rkt,alexhersh/rkt,ybubnov/rkt,liugenping/rkt,shtouff/rkt,jakon89/rkt,yifan-gu/rkt,liugenping/rkt,adfernandes/rkt,matthaias/rkt,marineam/rkt,Wilybald/rkt,lucasallan/rkt,matthaias/rkt,dgonyeo/rkt,ChengTiesheng/rkt,smarvin/rkt,Wilybald/rkt,il9ue/rkt,joshix/rkt,mjg59/rkt,alban/rkt,s-urbaniak/rkt,jjlakis/rkt,linki/rkt,achanda/rkt,wparad/rkt,mjg59/rkt,bsmr-go/rkt,monstermunchkin/rkt,yifan-gu/rkt,luebken/rkt,squeed/rkt,shtouff/rkt,Wilybald/rkt,Yhgenomics/rkt,MattDees/rkt,Shashwatsh/rkt,linki/rkt,bsmr-go/rkt,matthaias/rkt,akshaykarle/rkt,rkt/rkt,tmrts/rkt,squaremo/rkt,sstabellini/rkt,sgotti/rkt,tmrts/rkt,MattDees/rkt,dalanlan/rkt,krnowak/rkt,wparad/rkt,alban/rkt,liubq919/rkt,kinvolk/rkt,liubq919/rkt,blixtra/rkt,Yhgenomics/rkt,krnowak/rkt,rkt/rkt,euank/rkt,squeed/rkt,ybubnov/rkt,rkt/rkt,kbrwn/rkt,Shashwatsh/rkt,tv42/rkt,michelangelo13/rkt,yifan-gu/rocket,liubq919/rkt,adfernandes/rkt,jzelinskie/rkt,mike1729/rkt,wparad/rkt,s-urbaniak/rkt,lee212/rkt,nhlfr/rkt,rhvgoyal/rkt,joshix/rkt,iankronquist/rkt,adfernandes/rkt,ChengTiesheng/rkt,achanda/rkt,Wilybald/rkt,rhvgoyal/rkt,maquanyi/rkt,jonboulle/rkt,intfrr/rkt,chrisseto/rkt,tv42/rkt,shobhit85/rkt,tixxdz/rkt,rhvgoyal/rkt,joshix/rkt,mattthias/pkg-rkt,shtouff/rkt,fdserr/rkt,kbrwn/rkt,maquanyi/rkt,euank/rkt,akshaykarle/rkt,smarvin/rkt,linki/rkt,squaremo/rkt,marineam/rkt,tixxdz/rkt,jasonchaffee/rkt,dgonyeo/rkt,joshix/rkt,shobhit85/rkt,tixxdz/rkt,nhlfr/rkt,dalanlan/rkt,mattthias/pkg-rkt,coreos/rkt,alexhersh/rkt,chrisseto/rkt,yifan-gu/rocket,michelangelo13/rkt,alexhersh/rkt,kinvolk/rkt,kinvolk/rkt,cab105/rkt,iaguis/rkt,crawford/rkt,squaremo/rkt,sinfomicien/rkt,nhlfr/rkt,sinfomicien/rkt,maquanyi/rkt,mike1729/rkt,intelsdi-x/rkt,jakon89/rkt,bsmr-go/rkt,intelsdi-x/rkt,sinfomicien/rkt,shobhit85/rkt,crawford/rkt,rot26/rkt,fdserr/rkt,markllama/rkt,akshaykarle/rkt,krnowak/rkt,liugenping/rkt,coreos/rkt,euank/rkt,rot26/rkt,markllama/rkt,yifan-gu/rkt,s-urbaniak/rkt,luebken/rkt,lucasallan/rkt,marineam/rkt,jonboulle/rkt,il9ue/rkt,dalanlan/rkt,endocode/rkt,kbrwn/rkt,lee212/rkt,jasonchaffee/rkt