Fix opening data, align dev setup with production

[machow]

Address #42, #37

• Dev environment
  • changes location of dags, plugins, and data to match composer
  • moved config mount to user's home directory
  • on dev use google_default authentication, and set GOOGLE_CLOUD_PROJECT env var
  • add COMPOSER_ENVIRONMENT="development" flag
• Added calitpy.py module in plugins, to provide high-level functions (e.g. save_to_gcfs, which uses the test bucket on development). This can made a package down the line.
• Updated README with instructions for generating the necessary gcloud config

[hunterowens]

waiting on #42