Grants DB access to Users in Instance create API

Reasons:
- When database and users are provided as arguments, created users do not
  get access on suggested databases in cli instance create command.
- This was happening because database was not passed along with user info.

Changes:
- Concatenated the database information with the user info.

Change-Id: I3475f0eab1201b963bb32b2155c175a9483ef92f
Closes-Bug: #1272421
Merge "Grants DB access to Users in Instance create API"