Changes made for issue #855:
- Added additional validation of attribute name in assertions using class/object attributes
- Added new Test in Tests/Framework/AssertTest.php to cover attribute validation
Fixing a typo when reporting invalid attribute name
Changin 'valid name of attrubute with valid attribute name'
Merge pull request #859 from agop/master

Attribute validations added to assert methods
Added the changelog entry for #859