Moved the config.primary_storage_root to its own initializer, separate from
the process.  This still allows environments to override the storage root.
It also sets up a way for configuration management code, or docker scripts to
instantiate specific storage solutions, and configure RADS to use that storage
in a modular fashion by overwriting the default initializer/rads_storage.rb.

Also moved the shibboleth config.urls into its own initializer. It does not change
from one environment to another, but could change from one instantiation of RADS to
another.  Configuration management code, or docker scripts could tailor this script
for each instance as needed.

ALL TESTS STILL PASS