Remove postData from IOAsyncRequestCfg

Use `data` instead of `postData`.

Close #1057.
Remove aria.core.IO.useXHRHeader/defaultXHRHeader

Use `headers` and `postHeaders` instead.

Close #1057.
Remove IOAsyncRequestCfg:postHeader and related aria.core.IO options

Use `headers` in cfg bean and `headers`/`postHeaders` in aria.core.IO
instead.

Close #1057.