Refactor benchmark/context/quota.py

Created new  directory context/quotas/
Moved to this directory quota.py module
Saperated NovaQuotas, CinderQuotas, NeutronQuotas
in separated files

Similar process done for tests refactoring

https://trello.com/c/ycDv6GD3

Change-Id: I322313d2817a071ab02a386b0fe0d397e3e3cdf0
Merge "Refactor benchmark/context/quota.py"