[project] updated roadmap
[action] added new protocol which "superset" RBThenable
[promise] use RBAction object instead of custom attributes
[promise] introduce a 2nd state on RBPromise which is a more global one than "state"
[promise] perform actions only if promise resolve state is not set to RBPromiseResolveStateNotReady
[tests] update RBPromise tests to match with new API
[resolver] issue #5 : resolver interface + unit tests from RBPromise
[resolver] issue #5 : migrated code from RBPromise about resolve algorithm
[promise] issue #5 : Use a RBResolver object
[promise] refactored tests to take into account RBResolver object
[travis] travis config
[travis] ensure cocoapods is installed (Travis issue)
[travis] use shared schemes
[travis] set sdks
[travis] install xctool last version + set cocoapods version to use
[travis] install latest xctool version
[project] updated pbx
Merge pull request #6 from KptainO/resolver

Resolver
[project] issue #4: osx support
[pod] issue #4: add osx as supported platform