video: Hook to open http proxy connection

Added hook to open http proxy connection.
Application can set proxy details in http headers
with following key:val pair
    use-proxy : IP:Port

MediaHTTP parsers header and set proxy details over
underlying http stack.

Hook helps to set proxy details from native mediaserver
and pass information to MediaHTTP module

Change-Id: Id83f35d493541fa601318c78861c31a7d331d8c8