Tests refactoring

[DenTray]

Need to make small refactoring of autotests.

1. Need to increase the minimal version of the Laravel-Helpers requirements to 3.2

2. Remove .json extension from arguments of calling all getJsonFixture methods

3. In the FactoryGeneratorTest in testCreateFactoryWithoutFactoryStub remove useless result variable

4. Move setTestNow to the setUp method of the TestCase class and remove it from the MigrationGeneratorTest

5. Move mockFilesystem method call to the setUp method of all test classes

6. Move mockNovaServiceProviderExists method call to the setUp method of the NovaResourceGeneratorTest and NovaTestGeneratorTest

[DenTray]

@RGO230 let's also remove .json extension from tests stubs. All other points looks good

[RGO230]

@DenTray , done. Please, check