Repository: MoshiBin/ssdpy

Issue:
M-SEARCH has unescaped "Man" field
According to the official docs, the "Man" field's value should be wrapped in quotes.

Wrong:
```python
data = (                      
    "M-SEARCH * HTTP/1.1\r\n" 
    "HOST:{}\r\n"             
    "MAN: ssdp:discover\r\n"
    "ST:{}\r\n"               
    "MX:{}\r\n"               
).format(host, st, mx)
```

Right:
```python
data = (                      
    "M-SEARCH * HTTP/1.1\r\n" 
    "HOST:{}\r\n"             
    'MAN: "ssdp:discover"\r\n'
    "ST:{}\r\n"               
    "MX:{}\r\n"               
).format(host, st, mx)        
```

Discussion:

Patch:
diff --git a/ssdpy/protocol.py b/ssdpy/protocol.py
index 50a1be6..ba2a2ff 100644
--- a/ssdpy/protocol.py
+++ b/ssdpy/protocol.py
@@ -18,7 +18,7 @@ def create_msearch_payload(host, st, mx=1):
     data = (
         "M-SEARCH * HTTP/1.1\r\n"
         "HOST:{}\r\n"
-        "MAN:ssdp:discover\r\n"
+        'MAN: "ssdp:discover"\r\n'
         "ST:{}\r\n"
         "MX:{}\r\n"
     ).format(host, st, mx)


Test patch:
diff --git a/tests/test_protocol.py b/tests/test_protocol.py
index e1580c3..25bea49 100644
--- a/tests/test_protocol.py
+++ b/tests/test_protocol.py
@@ -11,7 +11,7 @@ class TestProtocol(unittest.TestCase):
         data_headers = parse_headers(data)
         self.assertEqual(data_headers.get("host"), "239.255.255.250:1900")
         self.assertEqual(data_headers.get("st"), "ssdp:all")
-        self.assertEqual(data_headers.get("man"), "ssdp:discover")
+        self.assertEqual(data_headers.get("man"), '"ssdp:discover"')
         self.assertEqual(data_headers.get("mx"), "1")
 
     def test_notify_payload(self):