Update keywords.py

Hi,

I wrote a small script that needs to pluck apart transactions in an SQL script. I use get_type() on a parsed statement to identify SQL commands, but this failed for BEGIN/START, COMMIT and ROLLBACK. I figured this is because those keywords weren't declared as DML. So I did this quick'n'dirty fix. I don't really know if this fits your architecture, but if not, maybe you can point me to a better solution. :-)

Thanks,
Victor


commit comment was:
delare BEGIN, START, COMMIT and ROLLBACK as DML keywords to allow sqlparse to be used to identify transactions