Fix some tests, update some gems in gemspec

My first pull request in a while.  I was mostly trying to re-familiarize and fix some dep-warnings.

It is a bit of a pain that the gemspec is mostly with exact version dependencies.
I think this is the latest 3.2 version.  I was hoping it might fix the issue in the mail gem that is causing some of the warnings running rspecs.  Specifically the ones about encoding.  I did see that later versions of the gem fix it, but probably they are required by 4.x versions.  The underlying issue is that the method uses a boolean indicating the charset is 'defaulted' to decide whether to do the warnings.  We set the default to utf-8, so the warnings shouldn't be sent.  The code for the latest versions seem to have fixed it, but no joy for 3.2.x versions (the mail gem version is a dependency of actionmailer, so we don't set it).