Convert gem to use engines

[aaronchi]

This has not been extensively tested but solves the loading issue with Rails 3.2 and generally updates ActsAsTaggableOn to conventions for Rails 3.0+ by using engines to load the models and components

This change is not backwards compatible to < Rails 3.0

[artemk]

Did you run tests?

[aaronchi]

tests don't work as-is. I think the proper way to test a Rails engine is to create a dummy application or to use something like this:
https://github.com/freelancing-god/combustion

I don't have time to work on updating the tests right now and wanted to get feedback on this strategy before I moved any further anyway.

[artemk]

I think this is good update. It was in my future plans, so i will appreciate your updates. I really like Allan's way of testing engines. If you will have some time soon, i will be appreciate to you for fixing tests. Thx.

[aaronchi]

ok. Don't wait for me if you have time to tackle the tests ;)

I'm pretty sure everything is still functional though, because I didn't change any of the code, just the way it was loaded.

[artemk]

@aaronchi Can you rebase it to current master, i will merge this.

[salgadobreno]

hey, would this help with issues like #34?

[artemk]

@salgadobreno i think no.

[tilsammans]

@aaronchi i took over maintenance of this gem. I think the change to an engine is a valid idea, but is there something particuarly wrong with the current architecture? It works fine, even in Rails 4 (if you look past deprecated syntax). Are any real problems solved by the change to an engine?

[aaronchi]

Did this when I was having some issues with the gem. They seem to have been fixed since via refactoring. Using an engine solves some issues but it's not completely necessary. Thanks for maintaining the gem.

[tilsammans]

Fyi, I've started work on the engine conversion: https://github.com/tilsammans/acts-as-taggable-on/tree/3-0-stable