Fixes#19
This is experimental as it changes the whole concept of a Note - We have
till now always assumed that a Note can have attached metadata. With
this, there is no longer any metadata. So other parts of the application
need to start reacting accordingly. For example the Mardkown Editor
should not allow you to modify the title.
This also makes it easier to implement '.txt' file support.
Some people are using GitJournal to edit Hugo websites, this option is
for them as the Hugo front matter uses the 'lastmod' key to indicate
when the post was last modified.
