Add dependencies for test harness
Initial code commit.

 - index exposes OpenStack as a function to be called passing in configuration parameters.
 - prototype methods on OpenStack object are proxied so that another function is called first,
this lets us perform repetitive actions in the `before` function, such as setting up a Promise.
Wrap OpenStack declaration in an IIFE to move the variable declarations inside the closure.
Added _auth() and associated tests. Stubbed listAllTenants() to provide a prototyped function to call in tests.
Finished listAllTenants() and added associated tests.