Allow track history for unsaved buffer.
Which means, cursor-history can go/back the history of file as long as the editor is alive.
So, nuclide remote file should be also trackable(I'm not using really check since I don' use remote edit environment).
Limitation: if file is not saved to local-disk the history entry is become unavailable when editor is destroyed.
Fix #37 Related #16 (partially fix)
Allow track history for unsaved buffer. Which means, cursor-history can go/back the history of file as long as the editor is alive. So, nuclide remote file should be also trackable(I'm not using really check since I don' use remote edit environment).
Limitation: if file is not saved to local-disk the history entry is become unavailable when editor is destroyed.