Update JsonResponse.php

Added JSON_NUMERIC_CHECK flag to fix issues when json response is used in JavaScript apps and especially in AngularJS.
merged branch esgy/patch-1 (PR #8420)

This PR was submitted for the master branch but it was merged into the 2.2 branch instead (closes #8420).

Discussion
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Update JsonResponse.php

Added JSON_NUMERIC_CHECK flag to fix issues when json response is used in JavaScript apps and especially in AngularJS.

Commits
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2b1c973 Update JsonResponse.php