gemspec: Do not include CI config files (#32)
gemspec: Do not include CI config files (#32)

* Exludes:
* CI config files
* Travis config
* Docker-related configuration
* RSpec config
* Git ignore file
* Gemfile
* bin/ files

jesjos/active_record_upsert,jesjos/active_record_upsert,jesjos/active_record_upsert,jesjos/active_record_upsert