Improved compatibility with lograge's graylog2 handler by extracting context values from the logevent data hash.
Not all logevent data values are hashes apparently.
Merge branch 'master' into lograge_compat

Conflicts:
	lib/log4r-gelf/gelf_outputter.rb
Merge pull request #8 from mogotest/lograge_compat

Lograge compat