Add PSR-4 autoloading.
Adjust LICENSE to contain full Apache 2.0 license.
Configure QA tools without Travis/Slack integrations for now.
Adjust project structure.

./src/Surfnet/MessageBirdApiClient/ <library code here>
./src/Surfnet/MessageBirdApiClientBundle/ <bundle code here>
Add Symfony2 Bundle scaffolding.
Configure Travis CI.
Add Scrutinizer configuration.