Add UsagesResource class

[gothub]

During multiple developer meetings, it was determined that the quotas and usages REST endpoints should be updated to conform to this list:

QuotaList = listQuotas():   GET     /quotas?\
                                            subscriber=:subscriber&\
                                            quotaType=:quotaType&\
                                            requestor=:requestor
Quota     = createQuota():  POST    /quotas
Quota     = getQuota():     GET     /quotas/:id
Quota     = updateQuota():  PUT     /quotas/:id
boolean   = deleteQuota():  DELETE  /quotas/:id
Usage     = getUsage():     GET     /usage/:id
UsageList = listUsage():    GET     /usage?quotaType=:quotaType\
                                            &instanceId=:instanceId&\
                                            subscriber=:subscriber
Usage     = createUsage():  POST    /usage
Usage     = updateUsage():  PUT     /usage/:id
boolean   = deleteUsage():  DELETE  /usage/:id

This will require a new UsagesResource class that will handle the /usage endpoints. The usage methods will be removed from QuotasResource. The new class/method configuration will be:

• QuotasResource:
  • listQuotas()
  • createQuota()
  • getQuota()
  • updateQuota()
  • deleteQuota()
• UsagesResource:
  • listUsage()
  • createUsage()
  • getUsage()
  • updateUsage()
  • deleteUsage()

[gothub]

@csjx If the method naming convention follows the other resource classes (including QuotasResource), the names for the new UsagesResource would be:

• listUsages()
• create()
• retrieve()
• update()
• delete()

[gothub]

The UsagesResource class was created, and the associated usage functions removed from QuotasResource in commit 03bc8eaa194b1796f969e3097efd4450b9e5a9b8