Bug 19913: Fix embedded HTML5 videos at the OPAC

Bug 19913: Fix embedded HTML5 videos at the OPAC

Caused by
commit 752aef4593f1aa2d64700bf9738e7e03907eb1cd
Bug 18754: Translatability: Get rid of exposed tt directives in opac-detail.tt

A space is missing between 'source' and 'src'

Test plan:
Set  HTML5MediaEnabled  to OPAC
Put a video link to 856$u
See the OPAC detail page, tab video, click the video
=> Should play with this patch applied

Note that this does not affect intranet

Signed-off-by: George Williams <george@nekls.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>