The Guidelines for the InterPlanetary JavaScript Projects [1] specify
that there is one Lead Maintainer for every module. This commit add
that information to the repository.

[1]: https://github.com/ipfs/community/blob/master/js-code-guidelines.md

Use `getCodeVarint()` instead of directly accessing the lookup
table of the multicodec module. This leads to nicer error messages
if the given codec is not found.

Prior to this commit:

    buffer.js:183
        throw new TypeError(kFromErrorMsg);
        ^

    TypeError: First argument must be a string, Buffer, ArrayBuffer, Array, or array-like object.
        at Function.Buffer.from (buffer.js:183:11)
        at CID.get buffer [as buffer] (/home/vmx/src/pl/js-cid/src/index.js:123:18)
        at CID.toBaseEncodedString (/home/vmx/src/pl/js-cid/src/index.js:184:44)
        at Object.<anonymous> (/home/vmx/src/pl/js-cid/keccak.js:16:19)
        at Module._compile (module.js:652:30)
        at Object.Module._extensions..js (module.js:663:10)
        at Module.load (module.js:565:32)
        at tryModuleLoad (module.js:505:12)
        at Function.Module._load (module.js:497:3)
        at Function.Module.runMain (module.js:693:10)

With this commit:

    /home/vmx/src/pl/js-multicodec/src/index.js:73
        throw new Error('Codec `' + codecName + '` not found')
        ^

    Error: Codec `mycodec` not found
        at Object.exports.getCodeVarint (/home/vmx/src/pl/js-multicodec/src/index.js:73:11)
        at CID.get buffer [as buffer] (/home/vmx/src/pl/js-cid/src/index.js:121:38)
        at CID.toBaseEncodedString (/home/vmx/src/pl/js-cid/src/index.js:186:44)
        at Object.<anonymous> (/home/vmx/src/pl/js-cid/keccak.js:16:19)
        at Module._compile (module.js:652:30)
        at Object.Module._extensions..js (module.js:663:10)
        at Module.load (module.js:565:32)
        at tryModuleLoad (module.js:505:12)
        at Function.Module._load (module.js:497:3)
        at Function.Module.runMain (module.js:693:10)

This makes stringifying a CID super easy like `${cid}` or `cid+''`.

License: MIT
Signed-off-by: Alan Shaw <[email protected]>

fix: improve isCID() by using `class-is` module.

I end up referring to these docs often and the generated documentation
is not very useful or informative.

I wrote up more human readable docs and put them in the README to
replace the generated docs. This API isn't so large that we can't just
document it in the README.

Travis and CirclCI are no longer used. The supported versions of
node are defined in the JS Guidelines (currently all active LTS
releases).

pre-commit hooks get into the way too often. pre-push hooks safes
from accidental pushes with linting and test errors.