Update asset manager code written to depend on null collection property defaults

Fixes an error introduced by my change in #2997.
Adjusted the Config to behave like the 1.3.* series' Config
Check if a key exists in attributes in Model::assign+ refactoring
columns is not required param
if columnMap defined we use only mappe name

Conflicts:
	phalcon/mvc/model.zep
test
tests and def value-null again

Conflicts:
	phalcon/mvc/model.zep
tabs
Removed parentheses and added unit tests to verify the behavior
fix test
Test has been changed because subject of issue - setting RawValue('default').
Current test don't works because it updates primary key, but in current version updates of primary keys not supported (http://forum.phalconphp.com/discussion/2989/update-primary-keys)
tabs
getSqlExpression() should not be final

If we need to extend the dialect, we have to overload the getSqlExpression(). See https://github.com/phalcon/cphalcon/issues/2952 and http://forum.phalconphp.com/discussion/1748/date-sub-interval-mysql
enable collection test
enable collection serialize test
support PHP 5.3 for ConfigTest
change fopen logic
add image tests
check other tests
remove is_readable from CSV translate adaptor
remove parentheses
move condition for checking next image
Merge pull request #3022 from quantum13/model_refactoring

Check if a key exists in attributes in Model::assign + refactoring
Merge pull request #3016 from rianorie/2.0.0_2988_ConfigArrayBehavior

Adjusted the Config to behave like the 1.3.* series' Config
Merge pull request #3030 from akaNightmare/enable_tests

Enable tests
Merge pull request #3026 from dugwood/patch-3

getSqlExpression() should not be final
Merge pull request #2998 from stecman/2997-amend

[2.0.0] Update asset manager code written to depend on null property defaults of Collection