Ftw.upgrade

----------------

- Add a ``WorkflowChainUpdater`` for changing workflow chains without
resetting existing objects to the initial review state of the new
workflow.
[jone]

------------------

- Added helper for adding a type_action.
[phgross]

- Add `objects` method to `UpgradeStep` for easy querying the catalog
and doing stuff with progress logging combined.
[jone]

- Make ProgressLogger an iterator too, because it is easier to use.
[jone]

- Improve logging while installing upgrade steps.
Show duration for installing.
[jone]

- Fix upgrade step icons for Plone 4.3.
[jone]

- Add ``update_security`` helper.
[jone]

- Fix incomplete status info entry prodcued by
placeful workflow policy activator.
[jone]

----------------

- Implement a placeful workflow policy activator.
[jone]

- Added remove_broken_browserlayer method to step class.
[lgraf]

------------------

- Keep modification date on reindexObject wihtout idxs.
[mathias.leimgruber]

----------------

- onegov.ch approved: add badge to readme.
[jone]

- Remove 'step' and 'for' values from internal data structure.
This is needed for allowing us to serialize the data (json).
[jone]

- Add IPostUpgrade adapter hook.
[jone]

- Refactor dependency sorting into seperate function.
[jone]

- Add security declarations.
[jone]

- Fix wrong tool usage when installing a profile in step class.
[jone]

----------------

- Add catalog_unrestricted_get_object and catalog_unrestricted_search methods to step class.
[jone]

- Handle profiles of packages which were removed but have leftover generic setup entries.
[jone]