anchor.diff:  
               {
                  "eventTimestamp":"1409929066 ",
  -               "eventType":"STACK_STARTED"
  +               "eventType":"STACK_STARTED",
  +               "eventMessage:"Stack started",
                  "userName":"John Doe",
                  "userId":14,
                  "accountName":"Company gmbh."
  
positive.code:               "blueprint":"lambda-architecture"
              }
  
  ### Retrieve filtered usage information for the account [GET]
  
   + Response 200
  
        [Retrieve account usage][]
  
  
  ## User usage [/user/usage{?since,cloud,zone,vmtype,hours,account,user,blueprint}]
  ### Retrieve user usage [GET]
  
  Retrieve usage information for the authetnicated user.
  
  + Response 200
  
       [Retrieve account usage][]
  
  ## Deployer usage [/usage{?since,cloud,zone,vmtype,hours,account,user,blueprint}]
  ### Retrieve deployer usage [GET]
  
  Retrieve usage information for the deployer user.
  
  + Response 200
  
       [Retrieve account usage][]
  
negative.code:                "blueprint":"lambda",
              }
  
  ### Retrieve events [GET]
  
  + Response 200
  
      [Retrieve events][]
  
  # Group Usage
  
  Usage resources provide insights into user activities.
  
  ## User usage [/user/usage{?since,cloud,zone,vmtype,hours,account,user,blueprint}]
  
  + Parameters
      + since (optional, string) ... timestamp indicating the day the usage information is to be retrieved from
      + cloud (optional, string) ... the cloud provider (eg.: AWS)
      + zone (optional, string) ... the region where the stack is running
      + vmtype (optional, string) ... the instance type
      + hours (optional, integer) ... the minimum amount of running hours
      + account (optional, long) ... account identifier
      + user (optional, long) ... user identifier
      + blueprint (optional, long) ... blueprint identifier
  