Added support for s3/s3n to the mesos fetcher.
Added support for s3/s3n to the mesos fetcher.

Review: https://reviews.apache.org/r/21852

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