functional tests: Change $TMPDIR to ^TMPDIR^
functional tests: Change $TMPDIR to ^TMPDIR^

This is to avoid confusion - $TMPDIR is replaced before the command is
ran. Also, it's more consistent - we use this format for RKT_BIN.

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