add serializers for verror.info and verror.MultiError

[DonutEspresso]

PTAL @yunong @micahr

[coveralls]

Coverage decreased (-0.3%) to 97.748% when pulling ef899df on verror-info-multierr into 584f836 on master.

[DonutEspresso]

Now that TritonDataCenter/node-verror#10 has landed, let's add some serializers for stuff that's directly using VError.

At some point in the next major release we should remove the context logic within this module, and use VError's info property instead.

[coveralls]

Coverage increased (+0.2%) to 98.174% when pulling 032d2a3 on verror-info-multierr into 584f836 on master.

[coveralls]

Coverage increased (+0.2%) to 98.174% when pulling 1f3be5b on verror-info-multierr into 584f836 on master.

[micahr]

LGTM

[DonutEspresso]

BTW @yunong if you wanna try this out just copy pasta this:

var verror = require('verror');
var bunyan = require('bunyan');
var restifyErrors = require('restify-errors');

var log = bunyan.createLogger({
    name: 'logger',
    serializers: {
        err: restifyErrors.bunyanSerializer
    }
});

var underlyingErr = new Error('boom');
var multiErr = new verror.MultiError([
    new Error('boom'),
    new restifyErrors.InternalServerError(underlyingErr, {
        message: 'wrapped',
        context: {
            foo: 'bar',
            baz: 1
        }
    })
]);

log.error(multiErr, 'oh noes');

Once we're completely on VError's new features we can break the serializer out into its own module. Need some catchy names that don't take forever to type (require('bunyan-verror-serializer')).