Always use German time zone, even if system time zone is different

The 1C4A hash is computed based (among other things) the current German
time.  Let's use German time no matter which timezone the executing
system is using.

inema/inema.py

@@ -1,6 +1,7 @@
 #!/usr/bin/python
 
-import time
+from datetime import datetime
+from pytz import timezone
 import md5
 import json
 from lxml import etree
@@ -32,7 +33,9 @@ def gen_1c4a_hdr(partner_id, key_phase, key):
         return md5_hex[:8]
 
     def gen_timestamp():
-        return time.strftime("%d%m%Y-%H%M%S")
+        de_zone = timezone("Europe/Berlin")
+        de_time = datetime.now(de_zone)
+        return de_time.strftime("%d%m%Y-%H%M%S")
 
     nsmap={'soapenv': 'http://schemas.xmlsoap.org/soap/envelope/',
            'v3':'http://oneclickforpartner.dpag.de'}