Turn --verify=False/True to --verify=no/yes

One way to address #559 -- https://github.com/jkbrzt/httpie/issues/559
-- instead of warning or throwing an error, just accept "True" and "False"
as synonyms of yes/no

(Updated to reflect feedback given at https://github.com/jkbrzt/httpie/pull/560 )

httpie/client.py

@@ -159,8 +159,10 @@ def get_requests_kwargs(args, base_headers=None):
         'data': data,
         'verify': {
             'yes': True,
-            'no': False
-        }.get(args.verify, args.verify),
+            'true': True,
+            'no': False,
+            'false': False,
+        }.get(args.verify.lower(), args.verify),
         'cert': cert,
         'timeout': args.timeout,
         'auth': args.auth,