Hash Content RPC method (#2355)

* Moving file fetching to separate crate.

* ethcore_hashContent

* Tests running on mocked fetch.

* Limiting size of downloadable assets

dapps/src/handlers/mod.rs

@@ -21,7 +21,6 @@ mod echo;
 mod content;
 mod redirect;
 mod fetch;
-pub mod client;
 
 pub use self::auth::AuthRequiredHandler;
 pub use self::echo::EchoHandler;