Use urlsafe_base64 for url sensitive chars

[kyuden]

We can use the urlsafe one.

[joshbuker]

If you're interested, maybe look into switching the models over to using has_secure_token instead of this custom model.

Otherwise just needs an entry on CHANGELOG.md and it's good to go!

[joshbuker]

Using urlsafe here is definitely preferable, although I wonder if we can deprecate this model entirely by using rails built in has_secure_token?

[kyuden]

The behavior is the almost same around this change.
Are we supposed to need an entry on CHANGELOG.md in this case?

[joshbuker]

Unless I'm mistaken, this changes behavior that could affect how someone handles the tokens (if it's not URL safe to begin with, someone might be running a strip method before using it in URLs). It likely won't affect most users, but I would err on the side of caution.

Edit: Ah, my bad. I should have read up on what tr does first. Looks like this is basically identical functionality. I'll go ahead and merge, seeing as it doesn't affect how users should handle the method it shouldn't need a changelog either.