add constants

These are to be used by the notes and attachments, and tells the journal
how it should be displayed.
.gitignore: add HTML files
journals/notes/attachments: add scaffolding
remove JSON/jbuilder cruft

Right now, our app is not designed at all to handle any sort of JSON
request, so remove it. We can always add it back later.
add access control for models
add sidebar

Also, move out the footer and content views from `application.slim` into
their own files as partials.
models: hide table if empty
login/logout: css facelift
journals: do not allow index view for non-logged-in users
journal creation
remove 'looseleaf' cruft

The app has been called 'pf' for some time now.
journal: add validators and update views
css: tables
journals_controller: fix params whitelist
attachment: validate binary types key