Without allow_unicode=True, unicode characters are processed through the
str representer and on Python 2 are dumped as a Unicode code point (i.e.
a literal \u0414). This commit makes allow_unicode=True the default in
our salt.utils.yamlloader.safe_dump() helper. It also adds a new
salt.utils.yamlloader.dump() helper which wraps yaml.dump() and also
makes allow_unicode=True the default.
To make importing and using our custom yaml loader/dumper easier, a
convenience module called salt.utils.yaml has been added, which does a
wildcard import from both salt.utils.yamldumper and
salt.utils.yamlloader.
Refs to yaml.load/dump and yaml.safe_load/safe_dump have been updated to
salt.utils.yaml, to ensure that unicode is handled properly.
On PY2, when os.walk is invoked with a str as input, the paths in the
return data are all str types as well. This leaves undecoded unicode
data in those strings when files/dirs under the top dir that was passed
contain unicode characters in the filename.
>>> import os
>>> list(os.walk('temp'))
[('temp', [], ['\xd0\x94.txt', 'foo.txt'])]
>>> list(os.walk(u'temp'))
[(u'temp', [], [u'\u0414.txt', u'foo.txt'])]
The helper introduced here ensures that we always invoke os.walk with a
unicode top-level dir, so that we get unicode types in the return data.
Example:
``` yaml
pillars:
default:
commands:
{% if grains['os'] == 'RedHat' %}
pkg_grains: /usr/bin/rpm_grains
{% endif %}
```
In this case `pkg_grains` wouldn't be found on anything else that RedHat systems and would be NoneType which would return an error and break the module.
