app: Make HTTP POST method emulation optional

For some applications, the HTTP method emulation for POST requests is
undesirable, particularly when the request contains a large payload
(e.g. file uploads, etc.). For these applications, this feature can be
disabled by setting the `post_method_emulation` attribute of their
application objects to `False`.

src/milla/app.py

@@ -50,6 +50,9 @@ class BaseApplication(object):
 
     DEFAULT_CONFIG = {}
 
+    #: Enable HTTP method emulation for POST requests?
+    post_method_emulation = True
+
     def __init__(self):
         self.config = self.DEFAULT_CONFIG.copy()
         self.setup_routes()
@@ -163,8 +166,9 @@ class BaseApplication(object):
         # Sometimes, hacky applications will try to "emulate" some HTTP
         # methods like PUT or DELETE by specifying an _method parameter
         # in a POST request.
-        if request.method == 'POST' and '_method' in request.POST:
-            request.method = request.POST.pop('_method')
+        if self.post_method_emulation:
+            if request.method == 'POST' and '_method' in request.POST:
+                request.method = request.POST.pop('_method')
         return request
 
     def resolve_path(self, path_info):