Add Messages unit test factory class

git-svn-id: https://buddypress.svn.wordpress.org/trunk@8504 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
Declare $pag_sql empty string in BP_Blogs_Blog::get_by_letter()

This squelches PHP notices when searching for unpaginated results

git-svn-id: https://buddypress.svn.wordpress.org/trunk@8505 cdf35c40-ae34-48e0-9cc9-0c9da1808c22