Trove/Blueprints/vertica-db-support

Description
Add Vertica analytical database in trove datastores.

Use Case Requirements
The implementation would provide additional feature to trove to support new datastore Vertica and specific operations for this datastore.

Described operations:

A. Instance creation with Vertica datastore.

B. Common database operations:
 * 1) Database : create, list, delete
 * 2) User : create, list, delete
 * 3) Revoke, grant user access

C. Back-up and restore functionality for Vertica datastore.

Scope
Implement all sections of Use Case Requirements.

Impacts
This change would impact mainly guestagent, as new datastore will be added.

Configuration
Configuration will be changed as per datastores. There is a proposed re-structuring for "ignoring users" as per datastore.

Database
This change has no impact on existing database tables.

Public API
No API calls are altered. Response to API calls would be similar for Vertica datastore.

Internal API
No change

Guest Agent
Vertica datastore specific guestagent code needs to be added. It will be compatible with the existing API structure and taskmanager.