Correct a couple of old function's @since phpDoc from 1.3 to 1.5.

Versions 1.3 and 1.4 never existed, and were re-badged as 1.5 for that release.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7464 cdf35c40-ae34-48e0-9cc9-0c9da1808c22