CMS_1JET_8TEV

(cc @tgiani )This PR contains the implementation of the CMS inclusive jets at 8 TeV (no NNLO QCD K-factors so far). The data implementation (with all details related to exp uncs) was carefully validated; the theory implementation (at NLO) is based on applgrids provided by Mark Sutton, I've explicitly checked that the accuracy of the FK tables (specifically the number of interpolating points on the x grid) is good enough to reproduce the native applgrids with negligible errors. The (pure QCD NLO) data/theory comparison is available at
https://vp.nnpdf.science/t1P3EWLRSK6KyFGJXcgJJw== The chi2 per data point is not particularly good. However, it significantly drops down if statistical uncertainties are uncorrelated: https://vp.nnpdf.science/Dt7clR0nTeOCm3TKz2zaUQ== I believe that this is a fact of life - let's see how the picture change with NNLO QCD K-factors.