Fix error unit-test of AssetsTest line 142 (InvalidArgumentException:
Parameter 'path' must be a string)

Problem: Path not send to the Css or Js resource constructor
Solve: Add in args on first position the path variable

More: Clean up arguments declaration for addCss and addJs in Collection
Fix error test-unit of assets.

Problem: InvalidArgumentException: Parameter 'filter' must be an
instance of 'Phalcon\Assets\FilterInterface'
(/home/vagrant/cphalcon-2.x.x/unit-tests/AssetsTest.php:438)

Solve: Add implements FilterInterface for cssmin, jsmin and none filter
classes
Merge pull request #2461 from alkana/2.0.0

2.0.0 - Starting to fix assets test-unit