Update olaf.py

[cherrydrpepper18]

Hello. This script has been really useful so thank you for making it available. I made the following changes to the code:

• added additional variables at the beginning to make it easier to update the index and deal with logs with columns in a different order.
• added code to repair truncated json. We found that the majority of the malformed line errors we got were because the Audit Data column was truncated
• made it so the it skips reading the header only if a header is present
• checks IP columns to make sure they contain an IP before doing geo lookup
• added "source" column to the index to make it easier to track what log events came from