🔨 Give the unit tests TestCase a namespace

[winkbrace]

Give the unit tests TestCase a namespace, so it won't conflict with Laravel's TestCase.

By default in Laravel applications, the \TestCase class is provided as base test case for all unit tests.
The base \TestCase class in this libraries' unit test suite shows confliction errors in phpstorm, because the same class exists twice in the project.

By giving the base test case of this project a namespace, the conflict is resolved.

[coveralls]

Coverage remained the same at 100.0% when pulling 7d5a3e3 on winkbrace:namespace-testcase into cc2b9a6 on dmitry-ivanov:master.

[dmitry-ivanov]

Thanks!

[winkbrace]

Thank you too! 😃