CRM-12923, CRM-12943 - Track whether model changes have been saved to the server

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* CRM-12923: Create HTML prototype of "Job Position" UI
  http://issues.civicrm.org/jira/browse/CRM-12923
* CRM-12943: Make HTML prototype of job UI functional
  http://issues.civicrm.org/jira/browse/CRM-12943
CRM-12923 - Add CRM.Backbone.trackSoftDelete

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* CRM-12923: Create HTML prototype of "Job Position" UI
  http://issues.civicrm.org/jira/browse/CRM-12923
CRM-12943 - crm.backbone.js - Allow saving of CRM collections

Calling "collection.save()" will lead to "CRM.api(crmEntityName, "replace", ...)

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* CRM-12943: Make HTML prototype of job UI functional
  http://issues.civicrm.org/jira/browse/CRM-12943
Merge pull request #1251 from totten/master-bb-issaved

CRM-12934 - Multiple Backbone updates
CRM-13121 - CRM.api - Always encode data with JSON

The query-string encoder misencodes empty arrays -- and most likely
misencodes other things.

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* CRM-13121: CRM.api cannot call "replace" with empty list
  http://issues.civicrm.org/jira/browse/CRM-13121
Merge pull request #1256 from totten/master-crmapi-json

CRM-13121 - CRM.api - Always encode data with JSON
Fix group api to work with group_type param