CSPACE-5869: Set limit of 40 media items returned in media snapshot, for safety.

Please merge into master.

Log statements after sample load reflect change to Mediaview.js, show no untoward behavior in response:

{code}
127.0.0.1 - - [13/May/2013:11:51:24 -0700] "GET /cspace-services/media?pgSz=40&pgNum=0&rtSbj=ffc5ca6b-a9c9-4aaa-9981&wf_deleted=false HTTP/1.1" 200 1118
0:0:0:0:0:0:0:1 - - [13/May/2013:11:51:24 -0700] "GET /collectionspace/tenant/core/cataloging/media/ffc5ca6b-a9c9-4aaa-9981?pageNum=0&pageSize=40 HTTP/1.1" 200 1080
{code}

Thanks,
Rick