Added XQLFW database and new Paper

[Martlgap]

Dear ChanChiChoi, i added the following two items to your readme.md and would kindly like to ask you if you could merge this.

XQLFW: Cross-Quality LFW database & evaluation protocol - preprint released on arXiv and dataset released on github

Paper: "Image Resolution Susceptibility of Face Recognition Models" - preprint released on arXiv

thank you very much cheers, Martin