Clusters Guest Implementation

adds guest impl code for creating a sharded mongodb
cluster as the first implementation

Co-Authored-By: amcrn <amcreynolds@ebaysf.com>
Co-Authored-By: Mat Lowery <mlowery@ebaysf.com>
Co-Authored-By: svenkataramanaia <svenkataramanaia@ebaysf.com>

Partially implements: blueprint clustering

Change-Id: Id45f692df377a32310a30487e27cf0f017c93c86
Merge "Clusters Guest Implementation"