Detecting concurrent edition and failing properly if needed
Merge pull request #179 from taigaio/bug/1709/error-on-concurrent-edition

Detecting concurrent edition and failing properly if needed
Refactor of tags queries using djorm-pgarray queries
tg-1736 #closed -> 404 instead 500 when call api/v1/projects/slug instead api/v1/project/id
Merge pull request #185 from taigaio/bug/1736/get_object_or_404_return_500

tg-1736 #closed -> 404 instead 500 when call api/v1/projects/slug instead api/v1/project/id
Merge pull request #184 from taigaio/us/1009/pgarray-query-refactoring

Refactor of tags queries using djorm-pgarray queries
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