Use '.yaml' extension as default, not '.yml'

As someone said [1] on the internet:

    Say ".yaml" not ".yml".
    This is not MS-DOS, and YML is a Yahoo XML dialect.

Similarly, we use '.json', not '.jsn'.

[1]: https://github.com/ceph/s3-tests/commit/e17c56a

README.rst

@@ -75,7 +75,7 @@ Usage
 .. code:: bash
 
  # Use a pre-defined lint configuration
- yamllint -d relaxed file.yml
+ yamllint -d relaxed file.yaml
 
  # Use a custom lint configuration
  yamllint -c ~/myconfig file.yml
@@ -83,7 +83,7 @@ Usage
 .. code:: bash
 
  # Output a parsable format (for syntax checking in editors like Vim, emacs...)
- yamllint -f parsable file.yml
+ yamllint -f parsable file.yaml
 
 Configuration example
 ^^^^^^^^^^^^^^^^^^^^^

docs/configuration.rst

@@ -10,14 +10,14 @@ directory, or use the ``-c`` option:
 
 .. code:: bash
 
- yamllint -c ~/myconfig file.yml
+ yamllint -c ~/myconfig file.yaml
 
 Default configuration
 ---------------------
 
 Unless told otherwise, yamllint uses its ``default`` configuration:
 
-.. literalinclude:: ../yamllint/conf/default.yml
+.. literalinclude:: ../yamllint/conf/default.yaml
    :language: yaml
 
 Details on rules can be found on :doc:`the rules page <rules>`.
@@ -85,7 +85,7 @@ For instance:
 
 .. code:: bash
 
- yamllint -d "{extends: relaxed, rules: {line-length: {max: 120}}}" file.yml
+ yamllint -d "{extends: relaxed, rules: {line-length: {max: 120}}}" file.yaml
 
 Errors and warnings
 -------------------

docs/quickstart.rst

@@ -81,7 +81,7 @@ option:
 
 .. code:: bash
 
- yamllint -c ~/myconfig file.yml
+ yamllint -c ~/myconfig file.yaml
 
 .. note::
 

setup.py

@@ -44,7 +44,7 @@ setup(
 
     packages=find_packages(),
     entry_points={'console_scripts': ['yamllint=yamllint.cli:run']},
-    package_data={'yamllint': ['conf/*.yml'],
+    package_data={'yamllint': ['conf/*.yaml'],
                   'tests': ['yaml-1.2-spec-examples/*']},
     install_requires=['pyyaml'],
     tests_require=['nose'],

yamllint/config.py

@@ -129,7 +129,7 @@ def get_extended_config_file(name):
     # Is it a standard conf shipped with yamllint...
     if '/' not in name:
         std_conf = os.path.join(os.path.dirname(os.path.realpath(__file__)),
-                                'conf', name + '.yml')
+                                'conf', name + '.yaml')
 
         if os.path.isfile(std_conf):
             return std_conf