Bump version to 0.13.0 (mattermost#181)

Bump version to 0.12.0 (mattermost#149)

* Bump version to 0.12.0

* go mod tidy

Point to external profile image and bump version to 0.9.1 (mattermost#68

)

Update org subscription implementation (mattermost#67)

Bump version to 0.8.0