Add --range-type option that forces range type of the trusted domain

Adds --range-type option to ipa trust-add command. It takes two
allowed values: 'ipa-ad-trust-posix' and 'ipa-ad-trust'.

When --range-type option is not specified, the range type should be
determined by ID range discovery.

https://fedorahosted.org/freeipa/ticket/3650

API.txt

@@ -3278,12 +3278,13 @@ output: Entry('result', <type 'dict'>, Gettext('A dictionary representing an LDA
 output: Output('summary', (<type 'unicode'>, <type 'NoneType'>), None)
 output: Output('value', <type 'unicode'>, None)
 command: trust_add
-args: 1,12,3
+args: 1,13,3
 arg: Str('cn', attribute=True, cli_name='realm', multivalue=False, primary_key=True, required=True)
 option: Str('addattr*', cli_name='addattr', exclude='webui')
 option: Flag('all', autofill=True, cli_name='all', default=False, exclude='webui')
 option: Int('base_id?', cli_name='base_id')
 option: Int('range_size?', autofill=True, cli_name='range_size', default=200000)
+option: StrEnum('range_type?', cli_name='range_type', values=(u'ipa-ad-trust-posix', u'ipa-ad-trust'))
 option: Flag('raw', autofill=True, cli_name='raw', default=False, exclude='webui')
 option: Str('realm_admin?', cli_name='admin')
 option: Password('realm_passwd?', cli_name='password', confirm=False)