Optionally allow nonstandard http methods to be used in httpclient.

By default we check that the method is one of the standard ones (and
is capitalized correctly), but this can be overridden to work with a
server that has implemented nonstandard methods (e.g. CouchDB)

http://github.com/facebook/tornado/issues/issue/90

tornado/httpclient.py

@@ -299,7 +299,8 @@ def __init__(self, url, method="GET", headers={}, body=None,
                  if_modified_since=None, follow_redirects=True,
                  max_redirects=5, user_agent=None, use_gzip=True,
                  network_interface=None, streaming_callback=None,
-                 header_callback=None, prepare_curl_callback=None):
+                 header_callback=None, prepare_curl_callback=None,
+                 allow_nonstandard_methods=False):
         if if_modified_since:
             timestamp = calendar.timegm(if_modified_since.utctimetuple())
             headers["If-Modified-Since"] = email.utils.formatdate(
@@ -322,6 +323,7 @@ def __init__(self, url, method="GET", headers={}, body=None,
         self.streaming_callback = streaming_callback
         self.header_callback = header_callback
         self.prepare_curl_callback = prepare_curl_callback
+        self.allow_nonstandard_methods = allow_nonstandard_methods
 
 
 class HTTPResponse(object):
@@ -432,7 +434,7 @@ def _curl_setup_request(curl, request, buffer, headers):
     if request.method in curl_options:
         curl.unsetopt(pycurl.CUSTOMREQUEST)
         curl.setopt(curl_options[request.method], True)
-    elif request.method in custom_methods:
+    elif request.allow_nonstandard_methods or request.method in custom_methods:
         curl.setopt(pycurl.CUSTOMREQUEST, request.method)
     else:
         raise KeyError('unknown method ' + request.method)