Fix bug in Entrez API call retry logic

git-svn-id: https://humgenprojects.lumc.nl/svn/mutalyzer/trunk@460 eb6bd6ab-9ccd-42b9-aceb-e2899b4a52f1

mutalyzer/Retriever.py

@@ -12,6 +12,7 @@ Public classes:
 
 import os              # path.isfile(), link() path.isdir(), path.mkdir(),
                        # walk(), path.getsize(), path.join(), stat(), remove()
+import time
 import bz2             # BZ2Compressor(), BZ2File()
 import hashlib         # md5(), update(), hexdigest()
 import urllib2         # urlopen()