Supported relative container path in docker containerizer.
Supported relative container path in docker containerizer.

Review: https://reviews.apache.org/r/49961/

reneploetz/mesos,verizonlabs/mesos,zmalik/mesos,andschwa/mesos,dforsyth/mesos,Aman-Jain-14/customizedMesos,asamerh4/mesos,reneploetz/mesos,Aman-Jain-14/customizedMesos,craimbert/mesos,reneploetz/mesos,asamerh4/mesos,abudnik/mesos,abudnik/mesos,dforsyth/mesos,craimbert/mesos,abudnik/mesos,Aman-Jain-14/customizedMesos,neilconway/mesos,jpeach/mesos,neilconway/mesos,neilconway/mesos,Gilbert88/mesos,gsantovena/mesos,reneploetz/mesos,chhsia0/mesos,jpeach/mesos,dforsyth/mesos,zmalik/mesos,neilconway/mesos,kaysoky/mesos,neilconway/mesos,dforsyth/mesos,andschwa/mesos,verizonlabs/mesos,yuquanshan/customizedMesos,gsantovena/mesos,gsantovena/mesos,chhsia0/mesos,jpeach/mesos,zmalik/mesos,abudnik/mesos,verizonlabs/mesos,jpeach/mesos,abudnik/mesos,jpeach/mesos,Gilbert88/mesos,chhsia0/mesos,zmalik/mesos,Gilbert88/mesos,andschwa/mesos,asamerh4/mesos,dforsyth/mesos,chhsia0/mesos,craimbert/mesos,dforsyth/mesos,abudnik/mesos,craimbert/mesos,verizonlabs/mesos,Gilbert88/mesos,Gilbert88/mesos,Gilbert88/mesos,chhsia0/mesos,neilconway/mesos,asamerh4/mesos,andschwa/mesos,verizonlabs/mesos,Aman-Jain-14/customizedMesos,craimbert/mesos,asamerh4/mesos,Gilbert88/mesos,chhsia0/mesos,zmalik/mesos,andschwa/mesos,gsantovena/mesos,neilconway/mesos,kaysoky/mesos,craimbert/mesos,zmalik/mesos,chhsia0/mesos,Aman-Jain-14/customizedMesos,kaysoky/mesos,gsantovena/mesos,reneploetz/mesos,craimbert/mesos,reneploetz/mesos,reneploetz/mesos,andschwa/mesos,verizonlabs/mesos,yuquanshan/customizedMesos,kaysoky/mesos,yuquanshan/customizedMesos,yuquanshan/customizedMesos,Aman-Jain-14/customizedMesos,asamerh4/mesos,kaysoky/mesos,dforsyth/mesos,gsantovena/mesos,yuquanshan/customizedMesos,abudnik/mesos,verizonlabs/mesos,andschwa/mesos,asamerh4/mesos,kaysoky/mesos,yuquanshan/customizedMesos,gsantovena/mesos,jpeach/mesos,yuquanshan/customizedMesos,kaysoky/mesos,Aman-Jain-14/customizedMesos,jpeach/mesos,zmalik/mesos