Fixes broken build #92, adds support for 1.8.7

:information_desk_person: The [Travis CI build #92](https://travis-ci.org/kytrinyx/etsy/builds/10174747) is broken due to two issues:
* a guard is needed [for ActiveSupport v4 for Ruby 1.8.7]
* the expectation on BasicClient [needs to have the port added](https://travis-ci.org/kytrinyx/etsy/jobs/10174749)

This changeset addresses and fixes both these issues.