0.6.0

• Add driver for Amazon SQS @ukautz
• Add driver for Iron MQ @ukautz
• Add driver for Doctrine DBAL which brings support for major SQL backends.
• Implement acknowledge logic for messages and drivers that uses it. @ukautz
• Add prefetching for drivers that use slow endpoints and supports getting more than one message.
• Refactor Consumer and cover it with tests.
• Drop using mocks where appropiate and instead use InMemoryQueue and InMemoryFactory
• Remove example/in_memory.php.
• Bring consistency by using Envelope internally and Message externally (end user).