Refactoring workbooks service to be symmetric with other services

* Getting rid of dictionary as a parameter for create_workbook_v2() and
  update_workbook_v2(), instead a plain string (yaml definition) is used
* Fixed all the calls of these methods
* Fixed unit tests

Change-Id: I70dcbf844e2d10ab6619de7972f0253022c534cd
Renaming trusts.py to security.py and adding method add_security_info

Change-Id: Ia25afa6c24cbdba8eabfbd2adc0e7ca40a04b8b6
Merge "Refactoring workbooks service to be symmetric with other services"
Merge "Renaming trusts.py to security.py and adding method add_security_info"