Add lookup for Linux kernel names of mountable file systems (#742741)

Function Utils::get_filesystem_kernel_name() returns the name of the
file system as needed for use in the mount command:
    mount -t TYPE DEVICE DIR

Needed because the kernel / mount name is 'hfsplus' where as libparted /
GParted, as reported by Utils::get_filesystem_string(), calls it 'hfs+'.
So far just added debugging when mounting a file system to test the
function works.

    # ./gartedbin
    ======================
    libparted : 2.1
    ======================
    DEBUG: (hfsplus) # mount -v /dev/sdb5 "/mnt/5"
    DEBUG: (nilfs2) # mount -v /dev/sdb1 "/mnt/1"

Bug 742741 - Nilfs2 file system is unusable on RHEL/CentOS 6