Properly escape inline <script>

Test Plan:
Loaded Phabricator page, checked the source code. Also:

    $c_uri = '//connect.facebook.net/en_US/all.js#xfbml=1&appId=';
    echo CelerityStaticResourceResponse::renderInlineScript(
      jsprintf(
        'console.log(%s); // </script>
        %s',
        $c_uri,
        "</script><b>x</b>"));

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5741