Test fail cases with logback appender
Add fail cases to log4j2 unit tests
Organise manually registered factories in a Map

To avoid conflicts when two factories of the same class are registered
only take the last factory of that type into account (replacing
previously registered factories with the same name)
Automatically remove the RAVEN_THREAD flag
Fix style issues
Remove the RAVEN_THREAD flag automatically
Use different logback.xml files between integration and unit tests
Add tests for DSN auto detect and raven initialisation
Throw exceptions from unit tests
Ensure the DSN during the lazy init is the right one
Fix style and indentation
Use a mock of the ravenFactory
Add a test for Dsn auto detection
Do not log the exception if initRaven fails

If the initialisation fail, the append call should fail entirely and
shouldn't rely on a null Raven
Test behaviour when the initialisation of Raven fails in logback