[Rails5] Add FALSE_VALUES constant to Service#boolean_accessor
[Rails5] Add FALSE_VALUES constant to Service#boolean_accessor

In Rails 5.0 the `ActiveRecord::ConnectionAdapters::Column::TRUE_VALUES`
constant has been removed [1] and the remaining `FALSE_VALUES` constant
has been moved to `ActiveModel::Type::Boolean` [2]

[1]: https://github.com/rails/rails/commit/a502703c3d2151d4d3b421b29fefdac5ad05df61
[2]: https://github.com/rails/rails/commit/9cc8c6f3730df3d94c81a55be9ee1b7b4ffd29f6

mmkassem/gitlabhq,axilleas/gitlabhq,mmkassem/gitlabhq,stoplightio/gitlabhq,jirutka/gitlabhq,jirutka/gitlabhq,dreampet/gitlab,axilleas/gitlabhq,axilleas/gitlabhq,jirutka/gitlabhq,dreampet/gitlab,iiet/iiet-git,mmkassem/gitlabhq,jirutka/gitlabhq,stoplightio/gitlabhq,axilleas/gitlabhq,iiet/iiet-git,stoplightio/gitlabhq,dreampet/gitlab,dreampet/gitlab,iiet/iiet-git,stoplightio/gitlabhq,iiet/iiet-git,mmkassem/gitlabhq