Modified the rietveld_scraper to auto chunk the code reviews.

To get the id file just use the following comand:

git log --pretty=format:"%n%s%n%b" --ignore-space-change | grep "^Review URL:" | grep 'codereview.chromium.org\|chromiumcodereview.appspot.com' | grep -o \[0-9]* >> ids.txt

* 250 issues per chunk is the default. Can be specified using the rietveld_scraper --chunk-size parameter.