cert: allow search by certificate

Allow search by certificate data or file in cert-find.

https://fedorahosted.org/freeipa/ticket/5381

Reviewed-By: David Kupka <dkupka@redhat.com>
Reviewed-By: Pavel Vomacka <pvomacka@redhat.com>

API.txt

@@ -723,10 +723,11 @@ output: Entry('result')
 output: Output('summary', type=[<type 'unicode'>, <type 'NoneType'>])
 output: PrimaryKey('value')
 command: cert_find
-args: 1,28,4
+args: 1,29,4
 arg: Str('criteria?')
 option: Flag('all', autofill=True, cli_name='all', default=False)
 option: Str('cacn?', cli_name='ca')
+option: Bytes('certificate?', autofill=False)
 option: Flag('exactly?', autofill=True, default=False)
 option: Str('host*', cli_name='hosts')
 option: DateTime('issuedon_from?', autofill=False)