Remove ActiveSupport dependency

[thatguysimon]

Why

Hi,
First off, let me just say - awesome job on this gem!
This approach of pure Ruby objects without any DSL is just what I was looking for.

One thing that's bothering me is the dependency on ActiveSupport. It kind of ruins the whole PORO approach.
Once you require stuff from core_ext (which modifies native Ruby classes), objects aren't really that pure anymore, are they?

I think a lot of the people that will find this gem are people who are not Rails users (like me) and this dependency on ActiveSupport can be a deal breaker in deciding whether to use this gem or not.

What

Remove the dependency on ActiveSupport. Use pure Ruby for stuff like hash manipulations, etc. (or maybe some small gems that don't modify native Ruby classes).

I can help out with refactoring and removing the usages of ActiveSupport methods if needed.

Thanks!