A working version of **IPNS working locally** is here!  🚀 😎 💪 

Steps:

- [x] Create a new repo (**js-ipns**) like it was made with go in the last week ([go-ipns](https://github.com/ipfs/go-ipns)) and port the related code from this PR to there
- [x] Resolve IPNS names in publish, in order to verify if they exist (as it is being done for regular files) before being published
- [x] Handle remaining parameters in publish and resolve (except ttl). 
- [x] Test interface core spec [interface-ipfs-core#327](ipfs-inactive/interface-js-ipfs-core#327)
- [x] Test interoperability with go. [interop#26](ipfs/interop#26)
- [x] Integrate logging
- [x] Write unit tests
- [x] Add support for the lifetime with nanoseconds precision
- [x] Add Cache
- [x] Add initializeKeyspace
- [x] Republish

Some notes, regarding the previous steps: 

- There is an optional parameter not implemented in this PR, which is `ttl`, since it is still experimental, we can add it in a separate PR.

Finally, thanks @Stebalien for your help and time answering all my questions regarding the IPNS implementation in GO.

Moreover, since there are no specs, and not that much documentation, I have been writing a document with all the IPNS workflow. It is a WIP by now, but it is currently available [here](ipfs/specs#184).

Related PRs:

- [x] [js-ipns#4](ipfs/js-ipns#4)
- [x] [js-ipfs-repo#173](ipfs/js-ipfs-repo#173)
- [x] [js-ipfs#1496](#1496)
- [x] [interface-ipfs-core#327](ipfs-inactive/interface-js-ipfs-core#327)
- [x] enable `interface-ipfs-core` tests for IPNS in `js-ipfs`