Notes list shows externally added files with wrong extensions and hidden files

[robwalton]

I have the atom-ctags extension installed. This automatically creates .tags files in my notes directory which then show up in the notes view. As an experiment I also manually added files with the wrong file extension in there too and those also show up.

In the code:
notes-fs.isNote() seems to exclude these files
notes-store.setUpFileWatcher() adds all files regardless of file extension to the NotesStore

I'll make a pull request, but I'm not confident in this area of the code.

[lexicalunit]

No worries, I can review your PR too :)

[lexicalunit]

Resolved by #32!