REST API should return machine-friendly date fields

Some dates on REST API are non machine friendly, namely on the testrun related endpoints:

• http://yourserver/rest/raven/1.0/api/test/ {key}

  /testruns

• http://yourserver/rest/raven/1.0/api/testrun?testExecIssueKey=TEST-123&testIssueKey=TEST-321"

as referred in:

• http://confluence.xpand-addons.com/display/XRAY2/Tests+-+REST
• http://confluence.xpand-addons.com/display/XRAY2/Test+Runs+-+REST

Example:

...
      "startedOn":"Yesterday 9:04 AM",
      "finishedOn":"Yesterday 10:39 AM",
...

   "created":"Yesterday 4:22 PM",
....

Dates should be machine friendly and follow the convention used in JIRA, which is ISO 8601 (e.g.
"2011-10-19T10:29:29.908+1100" )