break out MDS roles into its own group, shouldn't be installing the MDS on every OSD host in this example
break out MDS roles into its own group, shouldn't be installing the MDS on every OSD host in this example

shinespb/ceph-ansible,thetrav/ceph-ansible,ceph/ceph-ansible,nkmail/ceph-ansible,jsaintrocc/ceph-ansible,AcalephStorage/ceph-ansible,travmi/ceph-ansible,jfcoz/ceph-ansible,ltangeman/ceph-ansible,thetrav/ceph-ansible,albertomurillo/ceph-ansible,mcsage/ceph-ansible,msambol/ceph-ansible,syang/ceph_automation,PiotrProkop/ceph-ansible,nkmail/ceph-ansible,sheepkiller/ceph-ansible,jtaleric/ceph-ansible,bengland2/ceph-ansible,Miand/ceph-ansible-centos-6.6,SpringerPE/ansible-ceph,ceph/ceph-ansible,dang/ceph-ansible,WingkaiHo/ceph-ansible,lyandrew/ceph-ansible,WingkaiHo/ceph-ansible,WingkaiHo/ceph-ansible,mattt416/ceph-ansible,jfcoz/ceph-ansible,verdurin/ceph-ansible-1,AcalephStorage/ceph-ansible,leseb/ceph-ansible-1,fgal/ceph-ansible,guits/ceph-ansible,jtaleric/ceph-ansible,mattt416/ceph-ansible,font/ceph-ansible,dang/ceph-ansible,guits/ceph-ansible,rootfs/ceph-ansible,lejonet/ansible-ceph-common,msambol/ceph-ansible,albertomurillo/ceph-ansible,bengland2/ceph-ansible,bjne/ceph-ansible,verdurin/ceph-ansible-1,sheepkiller/ceph-ansible,mcsage/ceph-ansible,thiagodasilva/ceph-ansible,PiotrProkop/ceph-ansible,rootfs/ceph-ansible,travmi/ceph-ansible,Abhishekvrshny/ceph-ansible,fgal/ceph-ansible,ltangeman/ceph-ansible,jsaintrocc/ceph-ansible,Miand/ceph-ansible-centos-6.6,shinespb/ceph-ansible,bjne/ceph-ansible,thiagodasilva/ceph-ansible,albertomurillo/ceph-ansible,Abhishekvrshny/ceph-ansible,lyandrew/ceph-ansible,leseb/ceph-ansible-1,font/ceph-ansible