CRM-12413 - Return an error when api-key does not have an associated CMS user

----------------------------------------
* CRM-12413: CiviCRM does not error on an api-key given through the REST interface that is not connected to a CMS user
  http://issues.civicrm.org/jira/browse/CRM-12413
CRM-12412 - Implemented unit tests for REST interface authorization

----------------------------------------
* CRM-12412: Implement unit tests for REST interface
  http://issues.civicrm.org/jira/browse/CRM-12412
CiviSeleniumSettings - Use and document "siteKey" (instead of "sitekey")
CRM_Utils_REST - Fix PHP 5.4 error
WebTest_Utils_RestTest - s/assertAPIEquals/assertAPIErrorCode/
RestTest - Simplify test for property "siteKey" settings
RestTest - Formatting
RestTest - Move code from setUp() to _setUpAdminSessionIdAndApiKey(). Keep current behavior, but make it easier to change on per-test basis.
CiviSeleniumSettings - Add adminApiKey

RestTest - Use adminApiKey. Comment out test-cases for deprecated/dead functionality. Simplify/patch remaining test-cases.
RestTest - Test q=contact/$entity/$action syntax. Test calls with bad entities.
RestTest - Reformat and split testNotCMSUser in two.

The error expected for testNotCMSUser is currently produced for
"?q=civicrm/$entity/$action" but not "?entity=$x&action=$x", so we should be
testing both situations.
RestTest - Add test cases for omitted api_key. Tweak comments.
RestTest - Add test case for ping
Merge pull request #607 from totten/colbyw-rest

Add test case for REST interface