Handle Assembly R-values

[nmerket]

Walls and Roof R-values in OpenStudio-HPXML are specified as assembly R-values, but hescore-hpxml expects layers with nominal R-values. So, most surfaces are coming through with R-0.

[shorowit]

https://github.com/NREL/OpenStudio-HEScore/blob/master/rulesets/HEScoreRuleset/resources/lu_wall_eff_rvalue.csv
https://github.com/NREL/OpenStudio-HEScore/blob/master/rulesets/HEScoreRuleset/resources/lu_roof_eff_rvalue.csv