Initial Commit. First version of the client.

This is the first version of the CueCloud API PHP client, ready to be merged into cuecloud/cuecloud-php.

Includes the client itself, integration tests mimicking the Python API client, and a more complete `README` file.

The integration tests working:
```bash
$ phpunit ./tests/                                        (master✱)
PHPUnit 3.7.38 by Sebastian Bergmann.

Configuration read from cuecloud-php/phpunit.xml

..........

Time: 37.77 seconds, Memory: 3.25Mb

OK (10 tests, 16 assertions)
```