spec-1.2 rule [53]

Support "\/" for JSON compatability. Add tests and code for python and
python3.
Add file coding
Add requirements.txt for Travis
Add .travis.yml to configure Travis CI
Build the extension before testing
build_ext does not work on python3

- Use Cython's command instead to generate the C file needed
Merge pull request #2 from sigmavirus24/yaml-1.2

Set-up Travis CI for PyYAML
Fixed issue where aliases were not being resolved in constructors with deep=True.

>>> import yaml
>>> def test(loader, node):
>>>     return loader.construct_sequence(node, deep=True)
>>> yaml.add_constructor('!test', test)
>>> print(yaml.load("""
- &a [anchored]
- !test [*a]
""")

Expected output: [['anchored'], [['anchored']]]

Output before: [['anchored'], [[]]]