Call parent method to start Appenders (log4j/log4j2)
Improve logs while trying to get the DSN from JNDI
Do not obtain a Raven instance safely

Obtaining a raven instance should fail if the DSN isn't valid or something goes
wrong, it's the user's responsibility to handle that.
Handle potential exception from the RavenFactory
Start the SentryHandler properly

Ensure that the SentryHandler creates one instance of Raven only and doesn't
try to send logs to itself.
Load the JUL config file during integration tests
Rewrite the guard system for JUL to avoid recursive logging
Add integration tests for JUL
Change loglevel to ALL in log4j integraiton tests
Move the event building in a dedicated method in log4j
Add non-transitive dependencies from the test-jar
Move the event creation in a dedicated method
Add integration tests for logback