add builder dependency to assist in bundling
add builder dependency to assist in bundling

Bundler was getting confused trying to resolve the builder dependency,
so we specify a dependency even though there is no direct dependency.
This can be removed when the issue is fixed in bundler or if we no
longer depend on any other gems that depend on builder.

cucumber/cucumber-rails,analog-analytics/cucumber-rails,ipmobiletech/cucumber-rails,Kosmas/mime-types-runtime-dependency,zillou/cucumber-rails,ipmobiletech/cucumber-rails,zillou/cucumber-rails,analog-analytics/cucumber-rails,Kosmas/cucumber-rails,cucumber/cucumber-rails,Kosmas/cucumber-rails,cucumber/cucumber-rails