Use padding: false option over gsub

[daemonsy]

What's up?

I used the #to_param for my GIDs and it's awesome. Was reading the code and noticed a small improvement opportunity.

Since Ruby >= 2.3.0, Base64.urlsafe_encode64 accepts padding: false to exclude padding.

Base64.urlsafe_decode64 also works with strings with or without padding.

This PR removes the custom gsub in favor of using padding: false

The caveat is that this method will break for Ruby < 2.3

[byroot]

Thanks.