add requests class to sow the seeds of a custom matcher

vcr/request.py

@@ -0,0 +1,18 @@
+class Request(object):
+
+    def __init__(self, host, port, method, url, body, headers):
+        self.host = host
+        self.port = port
+        self.method = method
+        self.url = url
+        self.body = body
+        self.headers = frozenset(headers.items())
+
+    def __key(self):
+        return (self.host, self.port, self.method, self.url, self.body, self.headers)
+
+    def __hash__(self):
+        return hash(self.__key())
+
+    def __eq__(self, other):
+        return hash(self) == hash(other)