Added photo attribution for the background images to the "About" page. I
might be changing names and links there as  hear back from photographers
about their preferences. 

Also removed one background image I couldn't find again online.
Added "Powered by Metacat" to the footer
Added credit for the tiger photo used on the admin pages
The default about and tools page text has been updated to take out
references to the KNB and KNB-specific relative links.
Merge branch 'master' of https://code.nceas.ucsb.edu/git/nceas-staff/datadepot.git