Add log context implentation; see pull requests #124, #146 and #174
Fix LoggingEvent::toString() to include LogContext::toString()
Remove $context from LoggingEvent; Fix LoggerTest::configureWithContext()
Refactor enviromental info injection in context logs; Add unittests
Fix LoggingEvent contructor call
Merge pull request #239 from mrosoiu/log-context

Merged #239.