Add update_existing flag to AddMember method
Add enforce_required flag to add_member method
Add enforce_required flag to add_bulk_members method
Update add_member tests
Update add_bulk_members tests
Update readme
Update tests
Update references to 'user'
Update gemfile
Tasks to build, install and release gem
Add task to help configure RubyGems key
Merge pull request #9 from mattecalcio/api_flags

Update methods signature and Add rake tasks