Instance tracking information was improved to contain additional
information on instances such as type name, descriptive title
and number of VMs used by the application.
Added ability to retrieve non-aggregated statistics.
Also instance statistics API refactoring was made.
Implements blueprint app-catalog-billing
Change-Id: I8f3ea1a3947ceaf7deb2ee62b4ad41cbf230596e
4dd5c7b2f2