Increased the speed by calling grep & fixed past recommendations

The main change here is that I am using grep to cull the original log
file down first which greatly improves the speed as it won't have to run
the regular expression to parse the log line on nearly as many files.  I
have also started using csv, added default values to the help comments,
and various other tweaks suggested in the past audit.

Test Plan:
Run the various examples.

Auditors: jace, chris
Merge branch 'master' of github.com:Khan/analytics