Longer time limits for clock_tests

Travis was sometimes failing
Unify action phases into one class

check what can be called in particular phase at runtime
Improve World#trigger return value

- return PlaningFailed, ExecutionFailed, or Triggered products
- improve error ExecutionPlan::Steps::Error
  to keep reference to original error
- PlaningFailed contains error risen in Plan phase
  to be able to raise it again when needed
- ExecutionFailed contains error explaining why execution was rejected
  to be able to raise it again when needed
Merge pull request #96 from pitr-ch/master

Unify action phases into one class