Get out of the business of validating CAA records

Seem to be pretty inconsistently implemented/validated across providers so
just shrug and move on.

octodns/record.py

@@ -393,7 +393,7 @@ class CaaValue(object):
         reasons = []
         try:
             flags = int(value.get('flags', 0))
-            if flags not in (0, 128):
+            if flags < 0 or flags > 255:
                 reasons.append('invalid flags "{}"'.format(flags))
         except ValueError:
             reasons.append('invalid flags "{}"'.format(value['flags']))

tests/test_octodns_record.py

@@ -939,12 +939,23 @@ class TestRecordValidation(TestCase):
                 'type': 'CAA',
                 'ttl': 600,
                 'value': {
-                    'flags': 42,
+                    'flags': -42,
                     'tag': 'iodef',
                     'value': 'http://foo.bar.com/',
                 }
             })
-        self.assertEquals(['invalid flags "42"'], ctx.exception.reasons)
+        self.assertEquals(['invalid flags "-42"'], ctx.exception.reasons)
+        with self.assertRaises(ValidationError) as ctx:
+            Record.new(self.zone, '', {
+                'type': 'CAA',
+                'ttl': 600,
+                'value': {
+                    'flags': 442,
+                    'tag': 'iodef',
+                    'value': 'http://foo.bar.com/',
+                }
+            })
+        self.assertEquals(['invalid flags "442"'], ctx.exception.reasons)
         with self.assertRaises(ValidationError) as ctx:
             Record.new(self.zone, '', {
                 'type': 'CAA',