Fix that empty default value was converted to an empty array despite of strict mode

If Request parameter is an array without default value, then an error should be thrown that "parameter value is not an array" in strict mode
Updated installation instructions
Merge pull request #913 from javiereguiluz/update_composer_instructions

Updated installation instructions
fix ContainerBuilder mock generation in tests

By default, PHPUnit mocks all methods of the mocked class. This breaks
when one of the methods has an argument that is type-hinted with a
non-existing class or interface.
Merge pull request #914 from xabbuh/fix-tests

fix ContainerBuilder mock generation in tests
Add test that error is thrown when array parameter is missing in request
Merge pull request #910 from eugef/patch-1

Fixed validation for Request parameter that is an array without default value