https://github.com/Seldaek/monolog/pull/76#r743295
tests/Monolog/Handler/RavenHandlerTest.php into a separate file so that the test can pass when raven-php is installed and can be skipped when raven-php is not installed. Addresses @Stof's comment in https://github.com/Seldaek/monolog/pull/76#r740465
RavenHandlerTest::testException
protocol used by Sentry (http://github.com/dcramer/sentry). Uses raven-php (https://github.com/getsentry/raven-php).