Workaround for failing build on Ruby 1.8.7

* https://github.com/bundler/bundler/issues/2784
* https://github.com/rspec/rspec-expectations/commit/d2e3d97e5f0f1e23061f26376d2a752292c2a5d2
Ignore .bundle and .ruby-version
Update Travis-CI badge links to point to rcook/attr_encrypted
Merge branch 'p-rcook-ruby-1.8.7' into p-rcook-main