Fix new-lines rule on Python 3

Use io.open() when reading files in cli which has the same behaviour
in Python 2 and Python 3, and supply the newline='' parameter which
handles but does not translate line endings.

Add dos.yml test file with windows newlines.

Also add to file finding test expected output.

Add test for new-lines rule through the cli.

Validates files are read with the correct universal newlines setting.

Fixes adrienverge/yamllint#228

yamllint/cli.py

@@ -17,6 +17,7 @@
 from __future__ import print_function
 
 import argparse
+import io
 import os
 import platform
 import sys
@@ -176,7 +177,7 @@ def run(argv=None):
     for file in find_files_recursively(args.files, conf):
         filepath = file[2:] if file.startswith('./') else file
         try:
-            with open(file) as f:
+            with io.open(file, newline='') as f:
                 problems = linter.run(f, conf, filepath)
         except EnvironmentError as e:
             print(e, file=sys.stderr)