Implemented @utils.skip_test, @utils.skip_unless and @utils.skip_if functionality in glance/test/utils.py. Added glance/tests/unit/test_skip_examples.py which contains example skip case usages.
    
    Fixed issue where ./run_tests.sh would not execute pep8. Fixed couple of pep8 violations in test_skip_examples.py
    
    Change-Id: Id6eaa8768b663b4638fbca0e3bdf72b74969150a