SERVER-13679 Add record_id.h and move diskloc.h under mmap_v1
SERVER-13679 Replace DiskLoc with RecordId outside of MMAPv1

Operations:
    sed -i -e 's/\<DiskLoc\>/RecordId/g'
    sed -i -e 's/\<DiskLocs\>/RecordIds/g'
    sed -i -e 's/\<minDiskLoc\>/RecordId::min()/g'
    sed -i -e 's/\<maxDiskLoc\>/RecordId::max()/g'
    sed -i -e 's/\<getDiskLoc\>/getRecordId/g''

Changes under mmap_v1 were reverted and redone by hand as needed.
Merge remote-tracking branch 'upstream/master'