Prevent document update conflict from starting multiple surveys simultaneously
force decoding attachments as base64 in case they were saved incorrectly

http://manage.dimagi.com/default.asp?144906
remove unused imports

[ci skip]
Merge pull request #4624 from dimagi/session-locks

Prevent document update conflict from starting multiple surveys simultaneously
Merge pull request #4684 from dimagi/pact-fun-2

force decoding attachments as base64 in case they were saved incorrectly
Fix reference to renamed view
Merge remote-tracking branch 'origin/remove-hutch' into autostaging
Merge remote-tracking branch 'origin/subscription-no-contact-info' into autostaging
Merge remote-tracking branch 'origin/revert-4574-revert-4553-case-list-redesign' into autostaging
Merge remote-tracking branch 'origin/revert-4205-revert-3841-86347-2' into autostaging
Merge remote-tracking branch 'origin/reduce-location_' into autostaging
Merge remote-tracking branch 'origin/archive-location' into autostaging
Merge remote-tracking branch 'origin/masterlist-workflow' into autostaging
Merge remote-tracking branch 'origin/graphing+double-management' into autostaging
Merge branch 'bulk-app-translate' into autostaging
Merge remote-tracking branch 'origin/share-fixtures' into autostaging
Merge remote-tracking branch 'origin/autocomplete-case-sharing' into autostaging
Merge remote-tracking branch 'origin/logos' into autostaging
Merge remote-tracking branch 'origin/hq-dropdown+custom_user_data' into autostaging
Merge remote-tracking branch 'origin/hq-dropdown' into autostaging