0.7.0

• Adding to_json and summary traits to the Mp4Box type for reading out box values as text or json string via serde and serde_json. #29
• Add support for fragmented boxes: mehd, moof, mvex, tfhd, traf, trex, trun. #30
• Add support for reading fragmented tracks and samples. Added mp4sample example. #31
• Updated docs and renamed Github repository from mp4rs to mp4-rust. Rust crate remains as mp4.