Update to TTRSS 1.15

I'm going to regret this as 1.12 worked OK.  Same steps as commit
a8ad5b9e71f9a for upgrading:

    tar xf Tiny-Tiny-RSS-1.15.tar.gz
    rm -rf php
    mv Tiny-Tiny-RSS-1.15 php

Then check diffs in php/config.php (missing ?> at the EOF, don't revert
the openshift fixes), add new files, review diffs in all other files.