Don't show export link when not in a VSite.
Prevent access to /export outside of VSite.
Merge branch 'SCHOLAR-3.x' into 1372-query
Assure that we are in a multi-tenant install
Assure that we are in a multi-tenant install, in theme function
Merge pull request #1462 from openscholar/1372-query

#1372 Don't show export link when not in a VSite, Added some code to assure that we are in a multi-tentant install.  Otherwise looks good.