Add variable to set location of config files on aws

The env variable CONFIG_ROOT is used to determine the location of the
JSON configuration files. This is useful when a deployment of the
platform is used to access different environments when executing django
commands.
Change the default FROM address for bulk email
Wait between clicks for new component
Guard against StaleElementException in css_click
Add retry logic if element not found
Use a better metadata_cache_key

The old code created keys like "('course', 'org')", and the space
character caused a warning from Django during tests.  Also, strings are
probably better than tuples for keys.
make drag_and_drop component work with requirejs and changed static url
Unfortunately, delete tests are still failing sporadically in Jenkins.
Merge pull request #1263 from rocha/add-config-root-env-variable-to-aws-config

Add variable to set location of config files on aws
Merge pull request #1270 from edx/will/fix-multistep-component-test

Fix for failures in component.feature
Merge pull request #1268 from edx/will/fix-problem-acceptance

Guard against StaleElementException in css_click
Merge pull request #1272 from edx/ned/remove-cache-warning-from-tests

Use a better metadata_cache_key
correct placement of baseUrl variable, use it to configure requirejs
load common libs via require

using requirejs config to define deps
Merge pull request #1274 from edx/christina/disable-sporadic-tests

Unfortunately, delete tests are still failing sporadically in Jenkins.
Merge pull request #1260 from edx/sarina/email_FROM_address

Change the default FROM address for bulk email
Only change the collapse/expand state on the first child.

There are possibly children nested below that.
Merge pull request #1281 from edx/christina/toggle-expand

Only change the collapse/expand state on the first child.
Merge pull request #1282 from edx/will/wait-between-component-clicks

Wait between clicks for new component
Merge pull request #1273 from edx/db/fix-drag-and-drop-requirejs

make drag_and_drop component work with requirejs and changed static url