ActiveModel::Errors more accurate port with specs

[sfcgeorge]

Ported and specs pass.

Mostly additions and fixes. People like @adamcreekroad and myself who added patches should remove them and use the proper methods now; they match Rails API almost exactly in most cases and fix edge-cases.

Deprecations / changes (not breaking):

• initialize now follows Rails API - takes the record instance not a hash of errors, you add errors with add. This will be the biggest change to other code so both styles work for now.
• the class name has been corrected from ActiveModel::Error to ActiveModel::Errors, simply add an "s" in your code. Both work for now with warning.

Not implemented:

• something to do with YAML.
• to_xml.
• i18n - this is the biggest difference from the Rails API and would be nice to have. However I've managed to make it behave almost identically in most cases for English. It won't deal with custom translations, inflections, etc. Tests all pass though so can't be that different.
• something to do with Symbol since Opal doesn't have it, but difference shouldn't be noticeable mostly.
• strict option to rasie exception, probably not often used, wouldn't be hard to add though.

Hyperloop Changes

I have changed Hyperloop code to use the new classname, new constructor, and add and clear methods.

I think it's ready!

[sfcgeorge]

I've got all the tests passing. Now it's all standard Rails API - I've updated the Hyper Mesh code in the few places.