nose plugin to capture glance service logs
    
    Adding custom nose plugin to capture entire glance service logs
    for failed tests.
    
    Disabled by default, enable by setting:
    
      $ NOSE_GLANCELOGCAPTURE=true ; ./run_tests.sh
    
    Change-Id: I8a3bd9529ec6adb8b98804e0ddc266a7ea8eca08