Installs glance service from git.

Configuration
-------------
glance:
    db: mysql://glance:unset@localhost/glance
      - SQLAlchemy database connection string
    service-password: password
      - The service password for the glance user
    api:
        verbose: False
          - Show more verbose log output (sets INFO log level output)
        debug: False
          - Show debugging output in logs (sets DEBUG log level output)
        backend: swift
          - The backend store to use
        swift-store-user: service:glance
        swift-store-key:  userpassword
          - The credentials to use against swift if using the swift backend.
        workers: 1
          - The number of Glance API server processes to start.
        notifier-strategy: noop
          - Strategy to use for notification queue.
        log-file: ''
          - The path of the file to use for logging messages from Glance’s API server.
          - The default is unset, which implies stdout.
        default-log-levels:
          - Logging: fine tune default log levels
    registry:
        verbose: False
          - Show more verbose log output (sets INFO log level output)
        debug: False
          - Show debugging output in logs (sets DEBUG log level output)
        log-file: ''
          - The path of the file to use for logging messages from Glance’s Registry server.
          - The default is unset, which implies stdout.
        default-log-levels:
          - Logging: fine tune default log levels
