localize doc strings

A number of doc strings were not localized, wrap them in _().
Some messages were not localized, wrap them in _()

Fix a couple of failing tests:
The method name in RPC should not be unicode.
The doc attribute must use the .msg attribute for comparison.

Also clean up imports of _() The import should come from
ipalib or ipalib.text, not ugettext from request.

tests/test_ipalib/test_output.py

@@ -24,6 +24,7 @@ Test the `ipalib.output` module.
 from tests.util import raises, ClassChecker
 from ipalib import output
 from ipalib.frontend import Command
+from ipalib import _
 
 class test_Output(ClassChecker):
     """