Remove aria.core.IO.useXHRHeader/defaultXHRHeader
Remove aria.core.IO.useXHRHeader/defaultXHRHeader

Use `headers` and `postHeaders` instead.

Close #1057.

mlaval/ariatemplates,vcarle/ariatemplates,benouat/ariatemplates,fcapa/aria,lsimone/ariatemplates,mlaval/ariatemplates,divdavem/ariatemplates,benouat/ariatemplates,ariatemplates/ariatemplates,ariatemplates/ariatemplates,fcapa/aria,vcarle/ariatemplates,fbasso/ariatemplates,benouat/ariatemplates,ymeine/ariatemplates,fbasso/ariatemplates,vcarle/ariatemplates,divdavem/ariatemplates,ymeine/ariatemplates,simonarbuckle/ariatemplates,lsimone/ariatemplates,simonarbuckle/ariatemplates,fcapa/aria,ymeine/ariatemplates,mlaval/ariatemplates,divdavem/ariatemplates,simonarbuckle/ariatemplates,ariatemplates/ariatemplates,fbasso/ariatemplates