Changed mesos-local to use posix launcher as default.
Changed mesos-local to use posix launcher as default.

Review: https://reviews.apache.org/r/40681

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