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.
