Adds activesupport as runtime dependency.

[ream88]

I had problems using your gem without Rails. Loading a model which includes Mongoid::Tree fails with

NameError: uninitialized constant Mongoid::Tree::ActiveSupport

This commit fixes the dependency.

[benedikt]

Hi,

as the gem depends on mongoid, which depends on activmodel, which depends on activesupport this shouldn't be an issue. The gem itself is tested without rails and there were no problems up to now. Can you tell a bit more about your use case?

Bests,

Benedikt

[ream88]

Ok, what about requiring active_support at the beginning of tree.rb? Doing this in my local fork did fix all problems for me.

[benedikt]

Yes, that sounds like a good idea. Can you please change the pull request accordingly? Thanks! :)

[ream88]

Done :)

[ream88]

Should I squash them?

[benedikt]

That would be great :)

[ream88]

Sorry f**ked up git first, but now everything should work!

[benedikt]

👍 Thanks a lot, Mario!