fixed flash messages and cleaned up frontend repository

Frontend/export/fish.png

Frontend/export/net copy.png

Frontend/export/net.png

Frontend/export/net.svg

Frontend/export/preview_net.png

Frontend/static/OPTIS_logo.png

Frontend/static/OPTIS_logo2.png

Frontend/static/ProcessModel.PNG

Frontend/static/elog.csv

Frontend/static/elog.xes

Frontend/static/favicon.ico

Frontend/static/fish.jpg

Frontend/static/net.png

Frontend/static/optisicon.ico

Frontend/static/preview_net.png

Frontend/static/process_net.png

Frontend/static/smolconcern.png

Frontend/static/styles.css

Frontend/templates/base.html

Frontend/templates/index.html