Refactor girder roles into a more modular collection

[opadron]

Currently, the girder roles can only be used to install girder with a specific configuration:

• climos_test plugin installed
• sparktest plugin installed
• romanesco installed
• A specific set of enabled plugins:
  • celery_jobs
  • climos_test
  • user_quota
  • hdfs_assetstore
  • jobs
  • romanesco
  • sparktest
• One local asset store.
• One HDFS asset store.
• Romanesco plugin forced to use a rabbitmq server for the message queue.

The girder roles should be split into a larger collection of roles and/or modules that can be used in arbitrary combinations to achieve this, and any other configuration desired.

Examples of desired roles/modules include

• girder-install -- for (only) installing the base girder system
• girder-plugin -- for managing a girder instance's plugins
• girder-user -- for managing a girder instance's users
• girder-assetstore -- for managing a girder instance's assetstores
• girder-xyz -- for the large number of xyz's configurable through the girder client library

[opadron]

Issue created from discussions in #22.

[kotfic]

I would like to propose girder-plugin be the responsibility of roles dedicated to each plugin (e.g., romanesco-install, minerva-install, etc), i am working on a girder ansible module that should make this easier to accomplish

[opadron]

Sounds good to me, as long as the roles have "girder-plugin" in them to distinguish them from the actual software they might integrate with, i.e.: girder-plugin-romanesco, girder-plugin-minerva, etc.