feat(headers): Add From header field

src/header/common/mod.rs

@@ -29,6 +29,7 @@ pub use self::date::Date;
 pub use self::etag::ETag;
 pub use self::expect::Expect;
 pub use self::expires::Expires;
+pub use self::from::From;
 pub use self::host::Host;
 pub use self::if_match::IfMatch;
 pub use self::if_modified_since::IfModifiedSince;
@@ -315,6 +316,7 @@ mod date;
 mod etag;
 mod expect;
 mod expires;
+mod from;
 mod host;
 mod if_match;
 mod if_modified_since;