This makes it possible to remove of this obsolete flag from the
multi-tenant gateway.
As a consequence, displaying the GATEWAY_0_ACCESS env var will always
require a running storj-sim. Until now, it was required only the first
time. Then the value was stored in the 'access' config. But this is now
not possible anymore.
The changes in StripeMock are required to fix failures in integration
tests. StripeMock is in-memory and its data does not survive restarts of
storj-sim. The second and following starts of storj-sim had invalid
state of StripeMock, which failed requests that were required to
populate the GATEWAY_0_ACCESS env var. The changes in StripeMock makes
it repopulate the Stripe customers from the database.
Change-Id: I981a208172b76577f12ecdaae485f5ae4ea269bc
830817ec0d