Add a skeleton of ArmRedmine

Add ArmRedmine class to synchronize issues of Redmine.
It doesn't work yet because following features aren't implemented:

* Launching ArmRedmine threads
* Saving fetched date to DB

To share duplicated implementaion with IncidentSenderRedmine, I added RedmineAPI.
It's not needed to do something in this pull request, I wish this kind of utility function would be in mlpl::SmartTime.