[FEATURE] Auto detect the Response Content Type based on the request URI (Revision 2)

Currently Flow hardcode the Content-Type value to all the HTTP response to
text/html. This patch use the MediaTypes to detect the current content type
based on the request URI.

Change-Id: I1c89da2070687097ae83d1ca53f72f5005a1dc2b
Releases: master
Revision-Id: 4afd628c4f2482fe8bb488fc04e3d99a7b9bc80a