When passing a `plugins/...` path to bin/rspec, it's reasonable to assume that the developer wants the tests to be run with plugins loaded. This commit automatically takes care of that.
If `LOAD_PLUGINS` is explicitly specified, then that value will always be used.
This mimics the logic we already have for database migrations in the `bin/rake` stub
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging