Mls.fabfile

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- Added snapshotbackup option for database roles.
- Ability to update the maintenance client as well.

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- Moved common functionality to propertyshelf.fabfile.common.
- New tasks: rebuild client, list nodes for roles.

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- Set custom hostname for development environment so chef search works.
- Enabled data upload (Data.fs and blobs).

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- Added missing files.

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- Work with development, staging and production environments.
- Check for chef roles and create missing ones from configurations.
- Bootstrap MLS systems.
- Remove MLS clients if not needed any more.
- Manage database, frontend and worker components.
- Update client buildout packages.
- Download database files for local testing.