Memory for the mfs service

By default, Warden adds up the total memory consumed by all services and the OS and then gives 85% of what is left (evenly, by default or the percent value defined) to YARN and MRv1. If you do not intend to use MapR-DB, you can set the -noDB option in configure.sh to specify that 20% of the memory available should be allocated to mfs service.