Added admin interface to manage channels and enabled plugins (#9)

* Added base admin login/logout flows

* Ignore local database

* Channel model

* Admin interface for channels and plugins

* Added database tests along with workflows

* Added some docstrings

* Ignore .coverage file

* Creating plugins docs WIP

* Documentation

* Black everything

* Some documentation

* Coverage for the plugins package as well

* DB Fixes

* Absolute FROM in Dockerfile

* Database and logging fixes

* Slack: Support private channels

* Added pre-commit

* black'd

* Fixed UserQuery.create

* Fixed ChannelPluginQuery.create exists call

* Added ChannelPlugin menu for debugging

* Ignore sqlite databases

* Updated contributing docs

docs/README.md

@@ -0,0 +1,8 @@
+# Butterrobot Documentation
+
+## Index
+- [Contributing](./contributing.md)
+- [Platforms](./platforms.md)
+- Plugins
+    - [Creating a Plugin](./creating-a-plugin.md)
+    - [Provided plugins](./plugins.md)