provide fallback parser if YAML not installed

parseTestRecord.py:
- recover from ImportError when YAML not defined
- use monkeyYaml as backup

monkeyYaml.py:
- parser for subset of YAML used in test262 frontmatter

test_monkeyYaml.py:
- unit tests
Merge pull request #90 from smikes/monkeyYaml

provide fallback parser if YAML not installed