Refactoring: Move state file handling into a class
Move StateFile into a separate file
Add a method to get all deployments (as objects)
Sort deployments by name
nixops list: Make column alignment more sensible
nixops dump-state: New command to dump a JSON serialisation of deployments

Issue #99.
Generalize handling of --all
Rename ‘dump-state’ to ‘export’
nixops import: Support importing deployments dumped by ‘nixops export’

Fixes #99.
Document export/import