Slight tweak to IndexDocumentBundle version check, a=cpollett

diff --git a/src/library/IndexDocumentBundle.php b/src/library/IndexDocumentBundle.php
index a1ed42607..32ebd2e33 100644
--- a/src/library/IndexDocumentBundle.php
+++ b/src/library/IndexDocumentBundle.php
@@ -240,7 +240,7 @@ class IndexDocumentBundle implements CrawlConstants
                 $archive_info_path));
             $just_got_info = true;
         }
-        if ($this->archive_info['VERSION'] < 3.1) {
+        if (floatval($this->archive_info['VERSION']) < 3.1) {
             $this->archive_info['RECORD_COMPRESSOR'] =
                 C\NS_COMPRESSORS . "GzipCompressor";
         }