cli: Add mechanism for deprecated option name aliases

Add a new Param kwarg, deprecated_cli_aliases, that lists
deprecated aliases.
The aliases will appear in a "Deprecated options" in the help,
and otherwise act as the normal variant.

Preparation for: https://fedorahosted.org/freeipa/ticket/4231

ipalib/parameters.py

@@ -300,6 +300,7 @@ class Param(ReadOnly):
 
       - cli_name: option name in CLI
       - cli_short_name: one character version of cli_name
+      - deprecated_cli_aliases: deprecated CLI aliases
       - label: very short description of the parameter. This value is used in
         when the Command output is printed to CLI or in a Command help
       - doc: parameter long description used in help
@@ -384,6 +385,7 @@ class Param(ReadOnly):
     kwargs = (
         ('cli_name', str, None),
         ('cli_short_name', str, None),
+        ('deprecated_cli_aliases', frozenset, frozenset()),
         ('label', (basestring, Gettext), None),
         ('doc', (basestring, Gettext), None),
         ('required', bool, True),