Remove randomized fails in specs cause some miss configuration.

Depending on the order of the specs the notifier was configured or not. I've tried with seeds: 51050 and 19971. Seems to be solved in local.

I've moved configuration methods to a shared_context. We can reconfigure the notifier with metadata using `reconfigure_notifier: true`.
Let's actually use this one (the one that was in home_spec.rb): `bfec94a1ede64984b862880224edd0ed`. That's the token for this project, which is a public project: https://rollbar.com/Rollbar/rollbar-gem/