Rename internal dictionary from note_data to note_version
Rename internal dictionary from note_data to note_version

Because it just isn't possible to use one dictionary for everything.
I.e. now have the bufnum_to_noteid one.

References #75
References #78

sanchon/simplenote.vim,sanchon/simplenote.vim,mrtazz/simplenote.vim,mrtazz/simplenote.vim