Bug 11704: Make */svc/report print the correct headers

To test:
1 - Go through the first comments instructions to reproduce
    and verify the bug is present (OPAC and STAFF)
2 - Apply the patch
3 - Repeat step 1 and notice
   * characters are not broken anymore
   * the header is correct
4 - Sign off

Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>

opac/svc/report

@@ -67,5 +67,8 @@ unless ($json_text) {
     }
 }
 
-print $query->header;
+print $query->header(
+    -charset    => 'UTF-8',
+    -type       => 'application/json'
+);
 print $json_text;

svc/report

@@ -77,5 +77,8 @@ unless ($json_text) {
     }
 }
 
-print $query->header;
+print $query->header(
+    -charset    => 'UTF-8',
+    -type       => 'application/json'
+);
 print $json_text;