Add sentry

[jakebolam]

As the backend gets more complicated, and more service are dependent on it, the need for sentry (and readable stack traces increases)

We are using node8, so In order to do this, it would be best to remove webpack, which involves:

• Converting imports to commonjs,
• Remove any code that spreads
• remove babel and webpack

[francoiscampbell]

what about logrocket? we could try it out and see if it would work for us at TH