Implement "Foundations" package related changes.
Implement strong unicode support.
Continue implement strong unicode support.
Implement "Foundations" package changes.
Fix "templatesOutliner" component ui selection behavior.
Update "CHANGES.rst" file.
Update "Crittercism" application id.
Drop "sqlalchemy-migrate" support.

Closes #185.
Merge branch 'feature/migrate' into develop
Add international context tests.
Update manual / help files.
Update "CHANGES.rst" file.
Merge branch 'feature/unicode' into develop
Refactor "sibl_gui.ui.cache.AsynchronousGraphicsItemsCache.addContent" method.
Remove unused imports.
Improve images caches code handling consistency.
Implement large thumbnails support skeleton.
Continue large thumbnails support skeleton.
Update caches metrics related code.
Handle third party images formats thumbnails.