Plugin for GFAL2 to access data through xrootd. URLs that begin with root://
will use this plugin. All GFAL2 functions are supported in this plugin except
pread/pwrite and readlink/symlink (symlinks are not supported in xrootd).

Build requirements:
 - glib-2.0
 - xrootd-devel (available in EPEL)
 - gfal2-devel (available in EPEL-testing)

To build and install:
 - mkdir build
 - cd build
 - cmake ..
 - make
 - make install
 
When installed from source, GFAL_PLUGIN_DIR should be set to the installation
directory of the plugin, by default this is /usr/local/lib/gfal2-plugins but it
can be changed via configure options.
