cStringIO's constructor uses a 16-bit encoding when given a unicode

string.  This is inconsistent with its write method, which encodes all
strings as ascii (and rejects unicode strings iff they have any
non-ascii characters).  This change uses utf-8 as the default encoding
when constructing cStringIO objects in tornado.

tornado/httpclient.py

@@ -406,7 +406,7 @@ def _curl_setup_request(curl, request, buffer, headers):
 
     # Handle curl's cryptic options for every individual HTTP method
     if request.method in ("POST", "PUT"):
-        request_buffer =  cStringIO.StringIO(request.body)
+        request_buffer =  cStringIO.StringIO(request.body.encode('utf-8'))
         curl.setopt(pycurl.READFUNCTION, request_buffer.read)
         if request.method == "POST":
             def ioctl(cmd):

tornado/wsgi.py

@@ -261,7 +261,7 @@ def environ(request):
             "SERVER_PROTOCOL": request.version,
             "wsgi.version": (1, 0),
             "wsgi.url_scheme": request.protocol,
-            "wsgi.input": cStringIO.StringIO(request.body),
+            "wsgi.input": cStringIO.StringIO(request.body.encode('utf-8')),
             "wsgi.errors": sys.stderr,
             "wsgi.multithread": False,
             "wsgi.multiprocess": True,