[Findit] Add iterator and crash_iterator for delta test

appengine/findit/util_scripts/crash_queries/README.md

+###################### Set up enviroment variables. #####################
+##!/bin/bash
+#
+## Notice:
+## Source this script to setup the PYTHONPATH and other environment settings for
+## pulling data from ClusterFuzz through App Engine Remote API. Command:

[stgao, 2016/10/10 23:39:39]

Why we still pull data from ClusterFuzz? What's the high-level decision here?

We are going to port it to app engine soon, right?
In that case, all data will be in the app engine app.

(We could chat in person for this)

[Sharu Jiang, 2016/10/12 00:52:10]

Right, forgot to clean up the comments. 

+##   source setup_enviroments.sh
+##   . setup_enviroments.sh
+#
+## This must be set to the directory in which Findit source code is
+## checked out, eg: ~/chrome-internal if the checkout is in
+## ~/chrome-internal/findit.
+#export FINDIT_ROOT_DIR='root/path/to/findit'
+#
+## Since findit doesn't want to cover the tests of
+#export UTIL_SCRIPTS_DIR=$FINDIT_ROOT_DIR/util_scripts
+#
+##This must be set to the third_party directory under findit.
+#export THIRD_PARTY_DIR=${FINDIT_ROOT_DIR}/third_party
+#
+## This must be set to your appengine SDK directory.
+#APPENGINE_SDK_DIR='path/to/google_appengine'
+#
+#if [[ $PYTHONPATH != *$APPENGINE_SDK_DIR* ]]
+#then
+#  export PYTHONPATH=$UTIL_SCRIPTS_DIR:$FINDIT_ROOT_DIR:$THIRD_PARTY_DIR:$APPENGINE_SDK_DIR
+#fi
+#
+## This should be set to your app id.
+#export APP_ID="your app id"
+#
+## This must be set to the directory to put local checkout in.
+#export CHECKOUT_ROOT_DIR='path/to/checkout/root/path'