New feature, bug fixes and refactoring

New feature

• When a user changes his email address find the users change notice subscriptions with the old email address and update that address
• IMPORTANT: for this feature to work the CouchDB version must be 3.3.3 or above (new javascript engine)

Bug fixes

• Fix the formatting of code-blocks in the change notice email

Refactoring

• No need to have the followers data on the nodes
• Fix the missing blur when clicking on the tree view after editing a description or acceptance criteria
• Remove the workaround needed before the above fix