civicrm_api3_create_error, api/v3/Activity - Remove unnecessary args
civicrm_api3_create_error, api/v3/Generic/Update - Remove unnecessary indirection
civicrm_api3_create_error, api/v3/Activity - Remove support for optional parameter, $dao

The option is only used in one place.
civicrm_api3_create_error - Correction for weird SQL error reporting
Merge pull request #2741 from totten/master-api-error-cleanup

civicrm_api3_create_error - Misc cleanup/simplification