Create Custom Exceptions for gCalIntegratinator

[conzty01]

Is your feature request related to a problem? Please describe.
Create custom exceptions foe the gCalIntegrantinator to describe various exception cases for the interface. This can allow modules that import it to be able to more universally handle issues that arise. It might also be a good opportunity to learn about creating custom exceptions.

Describe the solution you'd like
If the integration piece runs into an issue that it cannot recover from, then it could raise a unique exception that informs the caller that there was an issue.

Describe alternatives you've considered
Continue using the returned statuses that are not very consistent.