<cron cart> Load env. vars. recursively

cron_runjobs.sh: Recursively load environment-variable directories,
as oo-trap-user does.

In particular, we want cronjobs that run on one gear of a scalable
application to load the environment variables of all cartridges, which
may be in subdirectories of ~/.env/.

This commit fixes bug 1069321.
Merge pull request #4813 from Miciah/bug-1069321--cron-cart-load-env-vars-recursively

Merged by openshift-bot