Async Soap Guzzle Versions Save

• Changed to use soap-http-binding 0.4. The implication is that a Psr\Http\Message\RequestFactoryInterface and a Psr\Http\Message\StreamFactoryInterface need to be injected into Meng\AsyncSoap\Guzzle\Factory when creating a Meng\AsyncSoap\Guzzle\SoapClient instance. This helps to decouple a specific implementation of PSR-7 and clients can determine which implementation of PSR-7 they wish to use.
• Removed support for PHP versions older than 7.1

• Changed to use soap-http-binding 0.3
• Removed support for PHP 5.5 as it is too old

• Add support for local filesystem WSDL and other kinds of URIs - this resolves https://github.com/meng-tian/async-soap-guzzle/issues/7.
• Refactor SoapClient.

Fix bugs in callAsync implementation (https://github.com/meng-tian/async-soap-guzzle/issues/4)

• add check for hasResponse: if response is not received, the request exception should be rethrown.
• move response parsing from finally block and only parse response when response is safely received.
• finally block only responsible for releasing stream resources.

• use coroutine to improve readability
• parse responses even when a 5xx or 4xx is returned
• close streams after invocation is completed
• fix tests

Use new version of SOAP HTTP binding to simplify this library, and also update tests and readme.