wrapping http

[amitu]

Currently we are using actix and are planning to move to hyper, but our application code must directly depend on either.

Currently all our HTTP request handlers take actix as input and output, which ties them too strongly with actix and switching away from actix is proving hard. We do not know what our eventual needs are going to be, so we can not pick a framework, so as much as possible we want to be as framework neutral as possible, so we can easily change framework when we need.

We will create fpm::http module with fpm::http::Request and fpm::http::Response types, which will be used by all our actual application code. And only fpm::http should know about which framework we are using.