gfs2-utils tests: Switch to autotest
    
    Replaces the custom tool_tests.sh test harness with the Autotest
    framework provided by Autoconf. See doc/README.tests for details.
    
    This is just a straight rework of the existing tests as Autotest test
    groups.
    
    Resolves: rhbz#1000066
    
    Signed-off-by: Andrew Price <anprice@redhat.com>