CI : travis run on PHP 7.2.5

update doc

update guide

[skip ci] release 1.0

all WorkflowEvent events fired now include the start status, the end

status and the transitions

update CHANGES.md

add method WorkflowInterface->getAllStatuses()

add Status::isInitialStatus() and arg to

WorkflowHelper::getNextStatusListData. rollback $emptyStringAsNull

Merge branch 'master' of git://github.com/raoul2000/yii2-workflow.git

add cache for workflow definition (WorkflowFileSource)