Changelog for dns-2.0.4

2.0.4 - Renaming a variable to fix preprocessor conflicts [#37](https://github.com/kazu-yamamoto/dns/pull/37) 2.0.3 - Handle invalid opcodes gracefully. [#36](https://github.com/kazu-yamamoto/dns/pull/36) 2.0.2 - Providing a new API: decodeMany. 2.0.1 - Updating document. 2.0.0 - DNSMessage is now monomorphic - RDATA is now monomorphic - Removed traversal instance for DNSMessage - EDNS0 encoding/decoding is now supported - Removed dnsMapWithType and dnsTraverseWithType functions - responseA and responseAAAA now take lists of IP addresses as their arguments - DNSHeader type no longer has qdCount, anCount, nsCount, and arCount fields