Tidy up accounts. Serialise/deserialise not ok

Still needs some work to get the syncing working. Got a feeling I might have to delete the code, re-plan and do it again (because there's a number of different ways it can happen).
Started on preferences page
Some copy
Merge branch 'master' into feature/account
Updated links to CodeMirror 4
Added missing sqlite update for settings.
Fixed the user settings after been changed
Merge branch 'master' into feature/account
Merge branch 'master' into feature/account
Ensure that default settings are presented as {}

This is only for existing users that haven't tweaked their editor settings
Update settings with addons.
Added jsbin CodeMirror theme css for editor preferences preview
Added better descriptions of addons.
Added addons functionality
Better ui for the addons form
Better labels
Update font size
Small tweaks
Fixed login layout for Firefox
Fixes