Merge pull request #1 from fabiokung/master

Propagate error messages and status from the SWF API
make idGen and client public in activity worker
fix RespondActivityTaskCanceled signature
fix type of CancelRequested
remove dup struct
log each decisionType returned by the FSMState Decider
more error handling/reporting in FSM
only output the json if c.Debug
logging
logging in pollers
add StartWorkflowWithId
refactor to Decider, pass []HistoryEvent instead of a single one
Merge pull request #2 from sclasen/scott-multiple-events-to-decider

refactor to Decider, pass []HistoryEvent instead of a single one
revert the decider taking []HistoryEvent, instead manage processing oldest -> newest events sequentially through the FSM, switching to the correct FSMState as appropriate
updates to the data/event data threading mechanism, see state.md
state