Included rare Lb Lambda ell ell decay files with LQCD form factors

Two decay files are included with the RareLbToLll model and LQCD form factors, as implemented by @tblake and @kreps. There is an error reported the decfile parser, but the code runs and with 50 events gave sensible results for the q2 distribution (average of 13 GeV^2, mostly at high q^2).