Fixed bug in require path for GELF (Graylog2)
require_once 'lib/Graylog2-gelf-php/...' is not correct because the Magento root is not in the include_path.
The directory "lib" is in the include_path, so removing it fixes this problem.
The problem occurred when you ran a Magento script which is not in the Magento root, for example a shell script.
Merge pull request #39 from jeroenvermeulen/bugfix_gelf_require_path

Fixed bug in require path for GELF (Graylog2)