Revert "Merge pull request #714 from heroku/app-tiers"

This reverts commit 6078acb06a9f51befdcfad2177f48b8c6699e4e1, reversing
changes made to d42163589eb7cab0293aad55faaaf000b843c220.

Pull request #714 breaks the specs even with heroku-api 0.3.8 in the gemspec, so reverting for now.
Remove ssl:remove entirely. ssl:clear can be used instead.
Deprecate ssl:add.
Document everything in ssl namespace as 'legacy'.
Remove ssl_spec entirely since it was only testing ssl:remove, which is gone, and ssl:add, which doesn't do anything anymore.
ssl:add deprecation: update formatting to be more in line with pre-existing stuff
Mark the entire ssl module as deprecated so it's not listed in `heroku help`