Do not propagate api password (#1797)

* Do not propagate API password in service requests.

It makes service validation fail. The choice is to either handle it as an
optional key in every service handler and make sure it doesn't end up in event
stream and notifications, or to strip it as early as possible.

* Some places still need a forwarded api password.

- Event forwarding/remote api uses the local api password to
  authenticate against the remote instance.
- The generated index.html at '/' embeds the api password.

homeassistant/components/http.py

@@ -28,7 +28,7 @@ from homeassistant.const import (
     HTTP_HEADER_CONTENT_LENGTH, HTTP_HEADER_CONTENT_TYPE, HTTP_HEADER_EXPIRES,
     HTTP_HEADER_HA_AUTH, HTTP_HEADER_VARY, HTTP_METHOD_NOT_ALLOWED,
     HTTP_NOT_FOUND, HTTP_OK, HTTP_UNAUTHORIZED, HTTP_UNPROCESSABLE_ENTITY,
-    SERVER_PORT)
+    SERVER_PORT, URL_ROOT, URL_API_EVENT_FORWARD)
 
 DOMAIN = "http"
 
@@ -218,6 +218,10 @@ class RequestHandler(SimpleHTTPRequestHandler):
         else:
             self.authenticated = False
 
+        # we really shouldn't need to forward the password from here
+        if url.path not in [URL_ROOT, URL_API_EVENT_FORWARD]:
+            data.pop(DATA_API_PASSWORD, None)
+
         if '_METHOD' in data:
             method = data.pop('_METHOD')