[Ndn-interest] go-ndn milestone 4

[Tai-Lin Chu]

Dear all,
It has been more than half a year since the last release. This release
focuses on overall code quality and performance improvements. As a
result, packet encoding/decoding speed has improved at least 100%, and
go-nfd forwarding speed has improved at least 40%.

https://github.com/go-ndn/ndn

changelog:
* all: reduce most small memory allocations
* all: increase test coverage to at least 70% in most packages
* tlv: finally remove bufio dependency in package decode
* tlv: use low-level binary.ByteOrder interface{}
* tlv: support encoding.BinaryMarshaler/BinaryUnmarshaler for special
field like ndn.Exclude
* ndn: remove ndn.SignKey as an exported variable
* ndn: explicitly sign packets
* lpm: add lock-less implementation
* ndn-cert-gen: add ecdsa key and self-sign cert generation


Cheers!