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.
'environment' predates the 'saltenv' nomenclature, and since we have
been using saltenv on the CLI for years, and now also have pillarenv, it
makes sense to make this change.
