Shiftboiler

Minor improvements to sentry integration feature.

Introduces integration with [Sentry](https://sentry.io/) via a feature switch.

Introduces some breaking changes to users functionality:

* Twitter OAuth authentication was removed ([83](https://github.com/projectshift/shift-boiler/issues/83)).
* Finalize social login step was removed ([85](https://github.com/projectshift/shift-boiler/issues/85)). We now skip this step and register/add new keys to profile directly which is a better user experience flow.
* Social provider tokens/expirations are no longer stored in user profile ([54](https://github.com/projectshift/shift-boiler/issues/54)). For that reason some assistance methods have been removed from user model as well.
* Flash messages are now disabled by default throughout user flow as they do interfere with async-driven auth flows
* An issue has been discovered with bootstrapping tests. This has been resolved is well.

Minor security release. Catches an issue described in [84](https://github.com/projectshift/shift-boiler/issues/84) when social provider is misconfigured and does not return user id.

Minor bugfix release. Fixes error in user CLI commands and boiler CLI app getter. Minor documentation improvements and dependencies updates.

Minor maintenance release that adds `python-dotenv` to the list of boiler dependencies.
It will now be installed automatically regardless of whether you use flask or not.