Perform some cleanup using php-cs-fixer

$ php-cs-fixer --verbose fix examples/
   1) event-dispatcher/event-dispatcher.php (function_declaration)
   2) event-handling/event-handling.php (new_with_braces)
   3) event-sourced-domain-with-tests/Invites.php (extra_empty_lines)

$ php-cs-fixer --verbose fix src/
   1) Broadway/EventSourcing/AggregateFactory/AggregateFactoryInterface.php (phpdoc_params)
   2) Broadway/EventSourcing/AggregateFactory/NamedConstructorAggregateFactory.php (unused_use)
   3) Broadway/EventSourcing/AggregateFactory/PublicConstructorAggregateFactory.php (new_with_braces)
   4) Broadway/EventSourcing/EventSourcingRepository.php (return)

$ php-cs-fixer --verbose fix test/
   1) Broadway/Auditing/CommandSerializerTest.php (visibility)
   2) Broadway/EventSourcing/AbstractEventSourcingRepositoryTest.php (unused_use)
   3) Broadway/EventSourcing/EventSourcingRepositoryTest.php (extra_empty_lines, new_with_braces)
   4) Broadway/Saga/Metadata/MetadataTest.php (unused_use, function_declaration)
   5) Broadway/Saga/Metadata/StaticallyConfiguredSagaMetadataFactoryTest.php (function_declaration)
   6) Broadway/Saga/MultipleSagaManagerTest.php (function_declaration)
   7) Broadway/Saga/State/CriteriaTest.php (psr0)
   8) Broadway/Saga/State/MongoDBRepositoryTest.php (function_declaration)
Merge pull request #78 from mbadolato/php_cs_fixer_cleanup

Perform some cleanup using php-cs-fixer
Make Saga base class abstract
Merge pull request #81 from mbadolato/make_saga_base_class_abstract

Make Saga base class abstract
Fixed wrong case in Elasticsearch namespace
Merge pull request #83 from nicolopignatelli/patch-1

Fixed wrong case in Elasticsearch namespace
More memory for composer
Merge pull request #87 from wjzijderveld/memory_limit

More memory for composer
Fixed wrong PHPDoc
Merge pull request #91 from ruudk/patch-1

Fixed wrong PHPDoc
Fix docblock typo
Merge pull request #92 from mbadolato/inheritdoc_typo_fix

Fix docblock typo
Add a command to drop the dbal event store schema.

This is useful when automating end-to-end tests.
Import `\Exception` in the Bundle commands.
Allow read models to have non-string IDs.

There is no reason why a read model's id should be a string. Being able
to cast the ID to a string is enough.
[hack] change event store uuid type to string.

The DBAL event store uses `guid` as its type for event uuids (which
makes sense). Unfortunately, we use string IDs in our tests for
convenience (like "offer_1"). The type should be configurable, but
we'll just use `string` for the time being.
Fix dev dependencies.

- require phpunit.
- require the sqlite extension.
use `require` to autoload test classes.

`require_once` returns `true`, so we can't add the test classes to the
autoloading.