Fixed minor typo in worker.py

Fixed minor typo in worker.py

Author: jyotiska <jyotiska123@gmail.com>

Closes #630 from jyotiska/pyspark_code and squashes the following commits:

ee44201 [jyotiska] typo fixed in worker.py

python/pyspark/worker.py

@@ -76,7 +76,7 @@ def main(infile, outfile):
         iterator = deserializer.load_stream(infile)
         serializer.dump_stream(func(split_index, iterator), outfile)
     except Exception as e:
-        # Write the error to stderr in addition to trying to passi t back to
+        # Write the error to stderr in addition to trying to pass it back to
         # Java, in case it happened while serializing a record
         print >> sys.stderr, "PySpark worker failed with exception:"
         print >> sys.stderr, traceback.format_exc()