adding HTTP response header (rebased onto dev_5_0)


This is the same as gh-843 but rebased onto dev_5_0.

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It fixes https://trac.openmicroscopy.org.uk/ome/ticket/12333

meta tag added in https://github.com/openmicroscopy/openmicroscopy/pull/2756

cc: @kennethgillen @chris-allan