feat(headers): adds Accept

Moved utils to shared/. Added quality_value.

src/header/shared/mod.rs

@@ -0,0 +1,26 @@
+//! Various functions, structs and enums useful for many headers.
+
+pub use self::encoding::Encoding;
+pub use self::encoding::Encoding::{
+    Chunked,
+    Gzip,
+    Deflate,
+    Compress,
+    Identity,
+    EncodingExt};
+
+pub use self::quality_item::QualityItem;
+pub use self::quality_item::qitem;
+
+pub use self::time::tm_from_str;
+
+pub use self::util::{
+    from_one_raw_str,
+    from_comma_delimited,
+    from_one_comma_delimited,
+    fmt_comma_delimited};
+
+pub mod encoding;
+pub mod quality_item;
+pub mod time;
+pub mod util;