Fix bug #726: Solve problem with with attachments content-type header
Fix bug #726: Solve problem with with attachments content-type header (again)
Fix bug #827: Improve invitation emails
Fix bug #783: Verify email existence on membership objects
Add access-control-max-age header to cors middleware for avoid options pre-flight.
Merge pull request #64 from taigaio/avoid-options-pre-flight

Add access-control-max-age header to cors middleware for avoid options pre-flight
Fix bug #752: Show only description_diff in emails
Fix bug #831: Assure us order change is registered in the history independently
WIP
WIP