v2.0.0

This major version marks our first open-source release, and thus the first version
with a changelog entry!

Features

• Plugins commands for Palm CLI are now largely driven by a plugin architecture.
  All commands in Palm are made available by one of several plugins. The core
  plugin and repo plugin are part of the Palm-cli repository and provide global commands
  as well as commands defined within the project's .palm directory. Additional plugins
  such as palm-dbt can be installed on the user's machine and configured for use
  on a per-project basis. See the plugin section of the docs for more information
• Palm config Palm now reads a config.yaml file from the current project's .palm
  directory. This configuration enables the plugin architecture and allows us more
  flexibility around protecting specific branches and determining the docker image
  name.
• Dependency detection Since docker is a core requirement for using Palm, we
  added checks to ensure docker and docker-compose are installed and running.
• Documentation Palm documentation has been enhanced with readthedocs, and now
  includes standard documentation for OSS projects, e.g. Contribution guide, code of conduct,
  and this changelog!
• Test suite Palm now has a good baseline of test coverage!

Improvements

• General cleanup - Code was reformatted for PEP8 compliance
• Naming - Renamed run_in_shell to run_in_docker, run_in_shell will be
  deprecated in a future version.