Made log location default to MESOS_HOME/logs, and to nothing if no location is specified.
Made log location default to MESOS_HOME/logs, and to nothing if no
location is specified.

git-svn-id: 03d7800a49d8905ef4fbcc296184319e19243493@1131928 13f79535-47bb-0310-9956-ffa450edef68

Aman-Jain-14/customizedMesos,enachb/mesos,abudnik/mesos,Aman-Jain-14/customizedMesos,yuquanshan/customizedMesos,samwhitlock/mesos-monitoring,dforsyth/mesos,pwendell/mesos,abudnik/mesos,samwhitlock/mesos-monitoring,kaysoky/mesos,chhsia0/mesos,kaysoky/mesos,gsantovena/mesos,chhsia0/mesos,kaysoky/mesos,woggle/mesos-old,reneploetz/mesos,kaysoky/mesos,charlescearl/VirtualMesos,charlescearl/VirtualMesos,pwendell/mesos,Aman-Jain-14/customizedMesos,gsantovena/mesos,charlescearl/VirtualMesos,neilconway/mesos,gsantovena/mesos,charlescearl/VirtualMesos,samwhitlock/mesos-monitoring,enachb/mesos,Gilbert88/mesos,charlescearl/VirtualMesos,enachb/mesos,reneploetz/mesos,yuquanshan/customizedMesos,gsantovena/mesos,neilconway/mesos,abudnik/mesos,abudnik/mesos,zmalik/mesos,asamerh4/mesos,pwendell/mesos,yuquanshan/customizedMesos,reneploetz/mesos,abudnik/mesos,samwhitlock/mesos-monitoring,wickman/mesos,dforsyth/mesos,woggle/mesos-old,Gilbert88/mesos,gsantovena/mesos,abudnik/mesos,woggle/mesos-old,woggle/mesos-old,reneploetz/mesos,woggle/mesos-old,dforsyth/mesos,andschwa/mesos,samwhitlock/mesos-monitoring,charlescearl/VirtualMesos,wickman/mesos,andschwa/mesos,pwendell/mesos,woggle/mesos-old,neilconway/mesos,neilconway/mesos,jpeach/mesos,craimbert/mesos,Aman-Jain-14/customizedMesos,kaysoky/mesos,zmalik/mesos,wickman/mesos,gsantovena/mesos,craimbert/mesos,reneploetz/mesos,chhsia0/mesos,andschwa/mesos,verizonlabs/mesos,pwendell/mesos,dforsyth/mesos,zmalik/mesos,chhsia0/mesos,wickman/mesos,zmalik/mesos,kaysoky/mesos,Aman-Jain-14/customizedMesos,asamerh4/mesos,Aman-Jain-14/customizedMesos,woggle/mesos-old,chhsia0/mesos,yuquanshan/customizedMesos,asamerh4/mesos,yuquanshan/customizedMesos,craimbert/mesos,Aman-Jain-14/customizedMesos,Gilbert88/mesos,asamerh4/mesos,enachb/mesos,jpeach/mesos,samwhitlock/mesos-monitoring,reneploetz/mesos,wickman/mesos,andschwa/mesos,andschwa/mesos,dforsyth/mesos,craimbert/mesos,jpeach/mesos,jpeach/mesos,craimbert/mesos,asamerh4/mesos,dforsyth/mesos,andschwa/mesos,gsantovena/mesos,andschwa/mesos,zmalik/mesos,verizonlabs/mesos,pwendell/mesos,woggle/mesos-old,pwendell/mesos,asamerh4/mesos,kaysoky/mesos,verizonlabs/mesos,jpeach/mesos,craimbert/mesos,charlescearl/VirtualMesos,yuquanshan/customizedMesos,verizonlabs/mesos,jpeach/mesos,neilconway/mesos,neilconway/mesos,enachb/mesos,chhsia0/mesos,wickman/mesos,Gilbert88/mesos,neilconway/mesos,charlescearl/VirtualMesos,Gilbert88/mesos,zmalik/mesos,abudnik/mesos,yuquanshan/customizedMesos,enachb/mesos,pwendell/mesos,pwendell/mesos,craimbert/mesos,charlescearl/VirtualMesos,dforsyth/mesos,Gilbert88/mesos,verizonlabs/mesos,chhsia0/mesos,zmalik/mesos,jpeach/mesos,woggle/mesos-old,verizonlabs/mesos,wickman/mesos,asamerh4/mesos,reneploetz/mesos,enachb/mesos,Gilbert88/mesos,verizonlabs/mesos