Fix uhepp plotter

For the ggFVBF 2j DF, we would like to use uhepp plotter. However, we keep getting the following error:

INFO: making plots Traceback (most recent call last): File "/home/chenj/projects/ctb-stelzer/chenj/newCAF/HWWAnalysisCode/share/visualize.py", line 94, in <module> main(config) File "/home/chenj/projects/ctb-stelzer/chenj/newCAF/HWWAnalysisCode/share/visualize.py", line 56, in main visualize.makePlots(config, reader, summary, channelsDict, outputdir, campaignsDict=campaignsDict) File "/home/chenj/projects/ctb-stelzer/chenj/newCAF/build/x86_64-centos7-gcc8-opt/python/CommonAnalysisHelpers/visualize.py", line 465, in makePlots plotterClass = getattr(QFramework, plotterClassName) AttributeError: 'module' object has no attribute 'uheppplotter'

We hope to fix this issue with this MR.