Imio.migrator

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- Add some more logging for actions `Clear and rebuild` or `Refresh` catalog.
[gbastien]
- Added parameter `catalogsToUpdate` to `refreshDatabase` so we can define what
catalog will be refreshed because by default, every catalogs are refreshed
and it is rarely necessary.
[gbastien]

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- Added `Migrator.reindexIndexesFor(idxs=[], **query)` method to be able to
easily reindex given `idxs` (indexes) on brains returned by
a given catalog `query`.
[gbastien]

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- Highlight log message about warning messages encountered durung migration.
[gbastien]
- Fixed `Migrator.refreshDatabase` method, wfs passed to
`WorkflowTool._recursiveUpdateRoleMappings` need to be a dict with
`wf id` as `key` and `wf object` as `value`, we had `wf object` for `key`
and `value`.
[gbastien]

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- Use same format when displaying duration of migration, duration is displayed
in days/hours/minutes/seconds in any cases.
[gbastien]

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- Be more preceise regarding duration of migration
(display in seconds and hours/minutes).
[gbastien]

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- Migrator class is no more an old-style class (it inherits from object now).
[gbastien]