LCP JSON mapping incomplete

[Daniel Weck]

https://github.com/readium/r2-streamer-go/blob/master/parser/epub/lcp.go#L33

	Rights struct {
		Print int        `json:"print"`
		Copy  int        `json:"copy"`
		Start *time.Time `json:"start"`
		End   *time.Time `json:"end"`
	}
	User struct {
		ID        string   `json:"id"`
		Email     string   `json:"email"`
		Name      string   `json:"name"`
		Encrypted []string `json:"encrypted"`
	}
	Signature struct {
		Algorithm   string `json:"algorithm"`
		Certificate string `json:"certificate"`
		Value       string `json:"value"`
	}

Missing: 'json:"rights"' 'json:"user"' and 'json:"signature"'